Ramda Adjunct 2.27.0

RA

RA

Source:

Methods

(static) allEqual(list) → {boolean}

Source:
Since:
Signature:
  • [a] -> Boolean
Category:
  • List
See also:

Returns true if all items in the list are equivalent using R.equals for equality comparisons.

Example
RA.allEqual([ 1, 2, 3, 4 ]); //=> false
RA.allEqual([ 1, 1, 1, 1 ]); //=> true
RA.allEqual([]); //=> true
Parameters:
Name Type Description
list Array

The list of values
Returns:
Type
boolean

(static) allEqualTo(val, list) → {boolean}

Source:
Since:
Signature:
  • a -> [b] -> Boolean
Category:
  • List
See also:

Returns true if all items in the list are equivalent to user provided value using R.equals for equality comparisons.

Example
RA.allEqualTo(1, [ 1, 2, 3, 4 ]); //=> false
RA.allEqualTo(1, [ 1, 1, 1, 1 ]); //=> true
RA.allEqualTo({}, [ {}, {} ]); //=> true
RA.allEqualTo(1, []); //=> true
Parameters:
Name Type Description
val *

User provided value to check the list against
list Array

The list of values
Returns:
Type
boolean

(static) allIdentical(list) → {boolean}

Source:
Since:
Signature:
  • [a] -> Boolean
Category:
  • List
See also:

Returns true if all items in the list are equivalent using R.identical for equality comparisons.

Example
RA.allIdentical([ 1, 2, 3, 4 ]); //=> false
RA.allIdentical([ 1, 1, 1, 1 ]); //=> true
RA.allIdentical([]); //=> true
RA.allIdentical([ {}, {} ]); //=> false
RA.allIdentical([ () => {}, () => {} ]); //=> false
Parameters:
Name Type Description
list Array

The list of values
Returns:
Type
boolean

(static) allIdenticalTo(val, list) → {boolean}

Source:
Since:
Signature:
  • a -> [b] -> Boolean
Category:
  • List
See also:

Returns true if all items in the list are equivalent to user provided value using R.identical for equality comparisons.

Example
RA.allIdenticalTo(1, [ 1, 2, 3, 4 ]); //=> false
RA.allIdenticalTo(1, [ 1, 1, 1, 1 ]); //=> true
RA.allIdenticalTo(1, []); //=> true
RA.allIdenticalTo({}, [ {}, {} ]); //=> false
Parameters:
Name Type Description
val *

User provided value to check the list against
list Array

The list of values
Returns:
Type
boolean

(static) allP(iterable) → {Promise}

Source:
Since:
Signature:
  • [Promise a] -> Promise [a]
Category:
  • Function
See also:

Composable shortcut for Promise.all.

The allP method returns a single Promise that resolves when all of the promises in the iterable argument have resolved or when the iterable argument contains no promises. It rejects with the reason of the first promise that rejects.

Example
RA.allP([1, 2]); //=> Promise([1, 2])
RA.allP([1, Promise.resolve(2)]); //=> Promise([1, 2])
RA.allP([Promise.resolve(1), Promise.resolve(2)]); //=> Promise([1, 2])
RA.allP([1, Promise.reject(2)]); //=> Promise(2)
Parameters:
Name Type Description
iterable Iterable.<*>

An iterable object such as an Array or String
Returns:

An already resolved Promise if the iterable passed is empty. An asynchronously resolved Promise if the iterable passed contains no promises. Note, Google Chrome 58 returns an already resolved promise in this case. A pending Promise in all other cases. This returned promise is then resolved/rejected asynchronously (as soon as the stack is empty) when all the promises in the given iterable have resolved, or if any of the promises reject. See the example about "Asynchronicity or synchronicity of allP" below.

Type
Promise

(static) allSettledP(iterable) → {Promise}

Source:
Since:
Signature:
  • [Promise a] -> Promise [Settlement a]
  • Settlement = { status: String, value: * }
Category:
  • Function
See also:

Returns a promise that is fulfilled with an array of promise state snapshots, but only after all the original promises have settled, i.e. become either fulfilled or rejected. We say that a promise is settled if it is not pending, i.e. if it is either fulfilled or rejected.

Example
RA.allSettledP([
  Promise.resolve(1),
  2,
  Promise.reject(3),
]); //=> Promise([{ status: 'fulfilled', value: 1 }, { status: 'fulfilled', value: 2 }, { status: 'rejected', reason: 3 }])
Parameters:
Name Type Description
iterable Iterable.<*>

An iterable object such as an Array or String
Returns:

Returns a promise that is fulfilled with an array of promise state snapshots

Type
Promise

(static) allUnique(list) → {boolean}

Source:
Since:
Signature:
  • [a] -> Boolean
Category:
  • List
See also:

Returns true if all items in the list are unique. R.equals is used to determine equality.

Example
RA.allUnique([ 1, 2, 3, 4 ]); //=> true
RA.allUnique([ 1, 1, 2, 3 ]); //=> false
RA.allUnique([]); //=> true
Parameters:
Name Type Description
list Array

The list of values
Returns:
Type
boolean

(static) anyP(iterable) → {Promise}

Source:
Since:
Signature:
  • [Promise a] -> Promise a
Category:
  • Function
See also:

Returns a promise that is fulfilled by the first given promise to be fulfilled, or rejected with an array of rejection reasons if all of the given promises are rejected.

Example
RA.anyP([
  Promise.resolve(1),
  2,
  Promise.reject(3),
]); //=> Promise(1)
Parameters:
Name Type Description
iterable Iterable.<*>

An iterable object such as an Array or String
Returns:

A promise that is fulfilled by the first given promise to be fulfilled, or rejected with an array of rejection reasons if all of the given promises are rejected

Type
Promise

(static) appendFlipped(list, el) → {Array}

Source:
Since:
Signature:
  • [a] -> a -> [a]
Category:
  • List
See also:

Returns a new list containing the contents of the given list, followed by the given element. Like R.append but with argument order reversed.

Example
RA.appendFlipped(['write', 'more'], 'tests'); //=> ['write', 'more', 'tests']
RA.appendFlipped([], 'tests'); //=> ['tests']
RA.appendFlipped(['write', 'more'], ['tests']); //=> ['write', 'more', ['tests']]
Parameters:
Name Type Description
list Array

The list of elements to add a new item to
el *

The element to add to the end of the new list
Returns:

A new list containing the elements of the old list followed by el

Type
Array

(static) argsPass(combiningPredicate, functions) → {boolean}

Source:
Since:
Signature:
  • ((* -> Boolean) -> [*] -> Boolean) -> [(* -> Boolean), ...] -> (*...) -> Boolean
Category:
  • Logic

Takes a combining predicate and a list of functions and returns a function which will map the arguments it receives to the list of functions and returns the result of passing the values returned from each function to the combining predicate. A combining predicate is a function that combines a list of Boolean values into a single Boolean value, such as R.any or R.all. It will test each value using RA.isTruthy, meaning the functions don't necessarily have to be predicates.

The function returned is curried to the number of functions supplied, and if called with more arguments than functions, any remaining arguments are passed in to the combining predicate untouched.

Example
RA.argsPass(R.all, [RA.isArray, RA.isBoolean, RA.isString])([], false, 'abc') //=> true
RA.argsPass(R.all, [RA.isArray, RA.isBoolean, RA.isString])([], false, 1) //=> false
RA.argsPass(R.any, [RA.isArray, RA.isBoolean, RA.isString])({}, 1, 'abc') //=> true
RA.argsPass(R.any, [RA.isArray, RA.isBoolean, RA.isString])({}, 1, false) //=> false
RA.argsPass(R.none, [RA.isArray, RA.isBoolean, RA.isString])({}, 1, false) //=> true
RA.argsPass(R.none, [RA.isArray, RA.isBoolean, RA.isString])({}, 1, 'abc') //=> false
Parameters:
Name Type Description
combiningPredicate function

The predicate used to combine the values returned from the list of functions
functions Array

List of functions
Returns:

Returns the combined result of mapping arguments to functions

Type
boolean

(static) async(generatorFn) → {function}

Source:
Since:
Signature:
  • Promise c => (a, b, ...) -> a -> b -> ... -> c
Category:
  • Function
See also:

Takes a generator function and returns an async function. The async function returned is a curried function whose arity matches that of the generator function.

Note: This function is handy for environments that does support generators but doesn't support async/await.

Example
const asyncFn = RA.async(function* generator(val1, val2) {
  const a = yield Promise.resolve(val1);
  const b = yield Promise.resolve(val2);

  return a + b;
});

asyncFn(1, 2); //=> Promise(3)
Parameters:
Name Type Description
generatorFn function

The generator function
Returns:

Curried async function

Type
function

(static) cata(leftFn, rightFn, catamorphicObj) → {*}

Source:
Since:
Signature:
  • (a -> b) -> (a -> c) -> Cata a -> b | c
Category:
  • Function
See also:

The catamorphism is a way of folding a type into a value.

Either

If the either is right then the right function will be executed with the right value and the value of the function returned. Otherwise the left function will be called with the left value.

Maybe

If the maybe is Some than the right function will be executed with the some value and the value of the function returned. Otherwise the left function with be called without an argument.

Result

If the result is Ok than the right function will be executed with the Ok value and the value of the function returned. Otherwise the left function will be called with the Error value.

Validation

If the validation is Success than the right function will be executed with the Success value and the value of the function returned. Otherwise the left function will be called with the Failure value.

Supported monadic libraries: monet.js, folktale, ramda-fantasy

Example
// Either
const eitherR = Either.Right(1);
const eitherL = Either.Left(2);

RA.cata(identity, identity, eitherR); //=> 1
RA.cata(identity, identity, eitherL); //=> 2

// Maybe
const maybeSome = Maybe.Some(1);
const maybeNothing = Maybe.Nothing();

RA.cata(identity, identity, maybeSome); //=> 1
RA.cata(identity, identity, maybeNothing); //=> undefined
Parameters:
Name Type Description
leftFn function

The left function that consumes the left value
rightFn function

The right function that consumes the right value
catamorphicObj Cata

Either, Maybe or any other type with catamorphic capabilities (cata or either method)
Returns:
Type
*

(static) ceil(number) → {number}

Source:
Since:
Signature:
  • Number -> Number
Category:
  • Math

Returns the smallest integer greater than or equal to a given number.

Note: ceil(null) returns integer 0 and does not give a NaN error.

Example
RA.ceil(.95); //=> 1
RA.ceil(4); //=> 4
RA.ceil(7.004); //=> 8
RA.ceil(-0.95); //=> -0
RA.ceil(-4); //=> -4
RA.ceil(-7.004); //=> -7
RA.ceil(null); //=> 0
Parameters:
Name Type Description
number number

The number to ceil
Returns:

The smallest integer greater than or equal to the given number

Type
number

(static) compact(list) → {Array}

Source:
Since:
Signature:
  • Filterable f => f a -> f a
Category:
  • List
See also:

Creates an array with all falsy values removed. The values false, null, 0, "", undefined, and NaN are falsy.

Example
RA.compact([0, 1, false, 2, '', 3]); //=> [1, 2, 3]
Parameters:
Name Type Description
list Array

The array to compact
Returns:

Returns the new array of filtered values

Type
Array

(static) concatAll(list) → {Array|string|undefined}

Source:
Since:
Signature:
  • [[a]] -> [a] | Undefined
  • [String] -> String | Undefined
  • Semigroup s => Foldable s f => f -> s | Undefined
Category:
  • List
See also:

Returns the result of concatenating the given lists or strings. Note: RA.concatAll expects all elements to be of the same type. It will throw an error if you concat an Array with a non-Array value. Dispatches to the concat method of the preceding element, if present. Can also concatenate multiple elements of a fantasy-land compatible semigroup. Returns undefined if empty array was passed.

Example
concatAll([[1], [2], [3]]); //=> [1, 2, 3]
concatAll(['1', '2', '3']); //=> '123'
concatAll([]); //=> undefined;
Parameters:
Name Type Description
list Array.<(Array|string)>

List containing elements that will be concatenated
Returns:

Concatenated elements

Type
Array | string | undefined

(static) concatRight(firstList, secondList) → {Array|String}

Source:
Since:
Signature:
  • [a] -> [a] -> [a]
  • String -> String -> String
Category:
  • List
See also:

Returns the result of concatenating the given lists or strings.

Note: R.concat expects both arguments to be of the same type, unlike the native Array.prototype.concat method. It will throw an error if you concat an Array with a non-Array value. Dispatches to the concat method of the second argument, if present.

Example
RA.concatRight('ABC', 'DEF'); //=> 'DEFABC'
RA.concatRight([4, 5, 6], [1, 2, 3]); //=> [1, 2, 3, 4, 5, 6]
RA.concatRight([], []); //=> []
Parameters:
Name Type Description
firstList Array | String

The first list
secondList Array | String

The second list
Returns:

A list consisting of the elements of secondList followed by the elements of firstList.

Type
Array | String

(static) contained(list, a) → {boolean}

Source:
Since:
Deprecated:
  • since v2.12.0; please use RA.included alias
Signature:
  • [a] -> a -> Boolean
Aliases:
  • included
Category:
  • List
See also:

Returns true if the specified value is equal, in R.equals terms, to at least one element of the given list or false otherwise. Given list can be a string.

Like R.contains but with argument order reversed.

Example
RA.contained([1, 2, 3], 3); //=> true
RA.contained([1, 2, 3], 4); //=> false
RA.contained([{ name: 'Fred' }], { name: 'Fred' }); //=> true
RA.contained([[42]], [42]); //=> true
Parameters:
Name Type Description
list Array | String

The list to consider
a *

The item to compare against
Returns:

Returns Boolean true if an equivalent item is in the list or false otherwise

Type
boolean

(static) curryRight(fn) → {function}

Source:
Since:
Signature:
  • (* -> a) -> (* -> a)
Category:
  • Function
See also:

Returns a curried equivalent of the provided function. This function is like curry, except that the provided arguments order is reversed.

Example
const concatStrings = (a, b, c) => a + b + c;
const concatStringsCurried = RA.curryRight(concatStrings);

concatStringCurried('a')('b')('c'); // => 'cba'
Parameters:
Name Type Description
fn function

The function to curry
Returns:

A new, curried function

Type
function

(static) curryRightN(length, fn) → {function}

Source:
Since:
Signature:
  • Number -> (* -> a) -> (* -> a)
Category:
  • Function
See also:

Returns a curried equivalent of the provided function, with the specified arity. This function is like curryN, except that the provided arguments order is reversed.

Example
const concatStrings = (a, b, c) => a + b + c;
const concatStringsCurried = RA.curryRightN(3, concatStrings);

concatStringCurried('a')('b')('c'); // => 'cba'
Parameters:
Name Type Description
length Number

The arity for the returned function
fn function

The function to curry
Returns:

A new, curried function

Type
function

(static) defaultWhen(predicatenon-null, defaultVal, val) → {*}

Source:
Since:
Signature:
  • (a -> Boolean) -> b -> a -> a | b
Category:
  • Logic
See also:

Returns the second argument if predicate function returns true, otherwise the third argument is returned.

Example
RA.defaultWhen(RA.isNull, 1, null); // => 1
RA.defaultWhen(RA.isNull, 1, 2); // => 2
Parameters:
Name Type Description
predicate function

The predicate function
defaultVal *

The default value
val *

val will be returned instead of defaultVal if predicate returns false
Returns:

The val if predicate returns false, otherwise the default value

Type
*

(static) delayP(milliseconds) → {Promise}

Source:
Signature:
  • Number -> Promise Undefined
  • {timeout: Number, value: a} -> Promise a
Category:
  • Function

Creates a promise which resolves/rejects after the specified milliseconds.

Example
RA.delayP(200); //=> Promise(undefined)
RA.delayP({ timeout: 1000, value: 'hello world' }); //=> Promise('hello world')
RA.delayP.reject(100); //=> Promise(undefined)
RA.delayP.reject({ timeout: 100, value: new Error('error') }); //=> Promise(Error('error'))
Parameters:
Name Type Description
milliseconds number | Object

number of milliseconds or options object
Returns:

A Promise that is resolved/rejected with the given value (if provided) after the specified delay

Type
Promise

(static) dispatch(functionsnon-null) → {*|undefined}

Source:
Since:
Signature:
  • [((a, b, ...) -> x1), ((a, b, ...) -> x2), ...] -> x1 | x2 | ...
Category:
  • Function
See also:

Can be used as a way to compose multiple invokers together to form polymorphic functions, or functions that exhibit different behaviors based on their argument(s). Consumes dispatching functions and keep trying to invoke each in turn, until a non-nil value is returned.

Accepts a list of dispatching functions and returns a new function. When invoked, this new function is applied to some arguments, each dispatching function is applied to those same arguments until one of the dispatching functions returns a non-nil value.

Example
// returns first non-nil value
const stubNil = () => null;
const stubUndefined = () => undefined;
const addOne = v => v + 1;
const addTwo = v => v + 2;

RA.dispatch([stubNil, stubUndefined, addOne, addTwo])(1); //=> 2

// acts as a switch
const fnSwitch = RA.dispatch([
  R.ifElse(RA.isString, s => `${s}-join`, RA.stubUndefined),
  R.ifElse(RA.isNumber, n => n + 1, RA.stubUndefined),
  R.ifElse(RA.isDate, R.T, RA.stubUndefined),
]);
fnSwitch(1); //=> 2
Parameters:
Name Type Description
functions Array

A list of functions
Returns:

Returns the first not-nil value, or undefined if either an empty list is provided or none of the dispatching functions returns a non-nil value

Type
* | undefined

(static) divideNum(divisor, dividend) → {number}

Source:
Since:
Signature:
  • Number -> Number -> Number
Category:
  • Math

Divides two numbers, where the second number is divided by the first number.

Example
RA.divideNum(2, 1); //=> 0.5
Parameters:
Name Type Description
divisor number

the number to divide by
dividend number

the number to divide
Returns:

A number representing the quotient of dividing the dividend by the divisor

Type
number

(static) dropArgs(fn) → {function}

Source:
Since:
Signature:
  • (...a -> b)-> () -> b
Category:
  • Logic
See also:

Accepts a function with any arity and returns a function with arity of zero. The returned function ignores any arguments supplied to it.

Example
const fn = (a = 1, b = 2) => a + b;

RA.dropArgs(fn)('ignore1', 'ignore2'); //=> 3
Parameters:
Name Type Description
fn function

The function with any arity
Returns:

Returns function with arity of zero

Type
function

(static) ensureArray(val) → {Array}

Source:
Since:
Signature:
  • a | [a] -> [a]
Category:
  • List
See also:

Returns a singleton array containing the value provided. If value is already an array, it is returned as is.

Example
RA.ensureArray(42); //=> [42]
RA.ensureArray([42]); //=> [42]
Parameters:
Name Type Description
val * | Array

the value ensure as Array
Returns:
Type
Array

(static) escapeRegExp(val) → {string}

Source:
Since:
Signature:
  • String -> String
Category:
  • String
See also:

Escapes the RegExp special characters.

Example
RA.escapeRegExp('[ramda-adjunct](https://github.com/char0n/ramda-adjunct)'); //=> '\[ramda\-adjunct\]\(https://github\.com/char0n/ramda\-adjunct\)'
Parameters:
Name Type Description
val string

the value to escape
Returns:
Type
string

(static) flattenDepth(depthnon-null, listnon-null) → (non-null) {Array}

Source:
Since:
Signature:
  • Number -> [a] -> [b]
Category:
  • List
See also:

Flattens the list to the specified depth.

Example
RA.flattenDepth(
  2,
  [1, [2], [3, [4, 5], 6, [[[7], 8]]], 9, 10]
); //=> [1, 2, 3, 4, 5, 6, [[7], 8], 9, 10];
Parameters:
Name Type Description
depth number

The maximum recursion depth
list Array

The array to flatten
Returns:

Returns the new flattened array

Type
Array

(static) flattenPath(pathnon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [Idx] -> {k: v} -> {k: v}
  • Idx = String | Int
Category:
  • Object
See also:

Flattens a property path so that its fields are spread out into the provided object. It's like spreadPath, but preserves object under the property path.

Example
RA.flattenPath(
  ['b1', 'b2'],
  { a: 1, b1: { b2: { c: 3, d: 4 } } }
); // => { a: 1, c: 3, d: 4, b1: { b2: { c: 3, d: 4 } } };
Parameters:
Name Type Description
path Array.<(string|number)>

The property path to flatten
obj Object

The provided object
Returns:

The flattened object

Type
Object

(static) flattenProp(prop, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [Idx] -> {k: v} -> {k: v}
  • Idx = String | Int
Category:
  • Object
See also:

Flattens a property so that its fields are spread out into the provided object. It's like spreadProp, but preserves object under the property path.

Example
RA.flattenProp(
  'b',
  { a: 1, b: { c: 3, d: 4 } }
); // => { a: 1, c: 3, d: 4, b: { c: 3, d: 4 } };
Parameters:
Name Type Description
prop string | number

The property to flatten
obj Object

The provided object
Returns:

The flattened object

Type
Object

(static) floor(number) → {number}

Source:
Since:
Signature:
  • Number -> Number
Category:
  • Math

Returns the largest integer less than or equal to a given number.

Note: floor(null) returns integer 0 and do not give a NaN error.

Example
RA.floor(45.95); //=> 45
RA.floor(45.05); //=> 45
RA.floor(4); //=> 4
RA.floor(-45.05); //=> -46
RA.floor(-45.95); //=> -46
RA.floor(null); //=> 0
Parameters:
Name Type Description
number number

The number to floor
Returns:

A number representing the largest integer less than or equal to the specified number

Type
number

(static) fnull(function, defaults) → {function}

Source:
Signature:
  • (a ... -> b) -> [c] -> a ... | c -> b
Category:
  • Function

Returns a function which is called with the given arguments. If any of the given arguments are null or undefined, the corresponding default value for that argument is used instead.

Example
const addDefaults = RA.fnull((a, b) => a + b, [4, 5])

addDefaults(1, 2); // => 3
addDefaults(null, 2); // => 6
addDefaults(2, null); // => 7
addDefaults(undefined, undefined); // => 9
Parameters:
Name Type Description
function function

to be executed
defaults Array

default arguments
Returns:

will apply provided arguments or default ones

Type
function

(static) hasPath(path, obj) → {boolean}

Source:
Since:
Deprecated:
  • since v2.12.0; ramda@0.26.0 contains hasPath
Signature:
  • [Idx] -> {a} -> Boolean
  • Idx = String | Int
Category:
  • Object
See also:

Returns whether or not an object has an own property with the specified name at a given path.

Example
RA.hasPath(['a', 'b'], { a: { b: 1 } }); //=> true
RA.hasPath(['a', 'b', 'c'], { a: { b: 1 } }); //=> false
RA.hasPath(['a', 'b'], { a: { } }); //=> false
RA.hasPath([0], [1, 2]); //=> true
Parameters:
Name Type Description
path Array.<(string|number)>

The path of the nested property
obj Object

The object to test
Returns:
Type
boolean

(static) inRange(low, high, value) → {boolean}

Source:
Since:
Signature:
  • Number -> Number -> Number -> Boolean
Category:
  • Relation

Checks if value is between low and up to but not including high.

Example
RA.inRange(0, 5, 3); //=> true
RA.inRange(0, 5, 0); //=> true
RA.inRange(0, 5, 4); //=> true
RA.inRange(0, 5, 5); //=> false
RA.inRange(0, 5, -1); //=> false
Parameters:
Name Type Description
low Number

Start of the range
high Number

The end of the range
value Number

The value to test
Throws:

When low is greater than or equal to high

Type
Error
Returns:
Type
boolean

(static) invokeArgs(path, args, obj) → {*}

Source:
Since:
Signature:
  • Array -> Array -> Object -> *
Category:
  • Object

Invokes the method at path of object with given arguments.

Example
RA.invokeArgs(['abs'], [-1], Math); //=> 1
RA.invokeArgs(['path', 'to', 'non-existent', 'method'], [-1], Math); //=> undefined
Parameters:
Name Type Description
path Array.<(string|number)>

The path of the method to invoke
args Array

The arguments to invoke the method with
obj Object

The object to query
Returns:
Type
*

(static) isArray(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is Array.

Example
RA.isArray([]); //=> true
RA.isArray(null); //=> false
RA.isArray({}); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isArrayLike(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Tests whether or not an object is similar to an array.

Example
RA.isArrayLike([]); //=> true
RA.isArrayLike(true); //=> false
RA.isArrayLike({}); //=> false
RA.isArrayLike({length: 10}); //=> false
RA.isArrayLike({0: 'zero', 9: 'nine', length: 10}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:

true if val has a numeric length property and extreme indices defined; false otherwise.

Type
boolean

(static) isAsyncFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is Async Function.

Example
RA.isAsyncFunction(async function test() { }); //=> true
RA.isAsyncFunction(null); //=> false
RA.isAsyncFunction(function test() { }); //=> false
RA.isAsyncFunction(() => {}); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isBigInt(val) → {boolean}

Source:
Signature:
  • * -> Boolean
Category:
  • Type

Checks if value is a BigInt.

Example
RA.isBigInt(5); // => false
RA.isBigInt(Number.MAX_VALUE); // => false
RA.isBigInt(-Infinity); // => false
RA.isBigInt(10); // => false
RA.isBigInt(10n); // => true
RA.isBigInt(BitInt(9007199254740991)); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isBoolean(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is Boolean.

Example
RA.isBoolean(false); //=> true
RA.isBoolean(true); //=> true
RA.isBoolean(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isDate(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is Date object.

Example
RA.isDate(new Date()); //=> true
RA.isDate('1997-07-16T19:20+01:00'); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isEmptyArray(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:
  • isNotEmptyArray

Checks if input value is an empty Array.

Example
RA.isEmptyArray([]); // => true
RA.isEmptyArray([42]); // => false
RA.isEmptyArray({}); // => false
RA.isEmptyArray(null); // => false
RA.isEmptyArray(undefined); // => false
RA.isEmptyArray(42); // => false
RA.isEmptyArray('42'); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isEmptyString(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:
  • isNotEmptyString

Checks if input value is an empty String.

Example
RA.isEmptyString(''); // => true
RA.isEmptyString('42'); // => false
RA.isEmptyString(new String('42')); // => false
RA.isEmptyString(new String('')); // => false
RA.isEmptyString([42]); // => false
RA.isEmptyString({}); // => false
RA.isEmptyString(null); // => false
RA.isEmptyString(undefined); // => false
RA.isEmptyString(42); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isEven(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is even integer number. An even number is an integer which is "evenly divisible" by two. Zero is an even number because zero divided by two equals zero, which despite not being a natural number, is an integer. Even numbers are either positive or negative.

Example
RA.isEven(0); // => true
RA.isEven(1); // => false
RA.isEven(-Infinity); // => false
RA.isEven(4); // => true
RA.isEven(3); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isFalse(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is the Boolean primitive false. Will return false for all values created using the Boolean function as a constructor.

Example
RA.isFalse(false); // => true
RA.isFalse(Boolean(false)); // => true
RA.isFalse(true); // => false
RA.isFalse(0); // => false
RA.isFalse(''); // => false
RA.isFalse(null); // => false
RA.isFalse(undefined); // => false
RA.isFalse(NaN); // => false
RA.isFalse([]); // => false
RA.isFalse(new Boolean(false)); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isFalsy(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

A falsy value is a value that translates to false when evaluated in a Boolean context. Falsy values are false, 0, "", null, undefined, and NaN.

Example
RA.isFalsy(false); // => true
RA.isFalsy(0); // => true
RA.isFalsy(''); // => true
RA.isFalsy(null); // => true
RA.isFalsy(undefined); // => true
RA.isFalsy(NaN); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isFinite(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is a finite Number.

Example
RA.isFinite(Infinity); //=> false
RA.isFinite(NaN); //=> false
RA.isFinite(-Infinity); //=> false

RA.isFinite(0); // true
RA.isFinite(2e64); // true

RA.isFinite('0');  // => false
                   // would've been true with global isFinite('0')
RA.isFinite(null); // => false
                   // would've been true with global isFinite(null)
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isFloat(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is a float.

Example
RA.isFloat(0); //=> false
RA.isFloat(1); //=> false
RA.isFloat(-100000); //=> false

RA.isFloat(0.1);       //=> true
RA.isFloat(Math.PI);   //=> true

RA.isFloat(NaN);       //=> false
RA.isFloat(Infinity);  //=> false
RA.isFloat(-Infinity); //=> false
RA.isFloat('10');      //=> false
RA.isFloat(true);      //=> false
RA.isFloat(false);     //=> false
RA.isFloat([1]);       //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is Function.

Example
RA.isFunction(function test() { }); //=> true
RA.isFunction(function* test() { }); //=> true
RA.isFunction(async function test() { }); //=> true
RA.isFunction(() => {}); //=> true
RA.isFunction(null); //=> false
RA.isFunction('abc'); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isGeneratorFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is Generator Function.

Example
RA.isGeneratorFunction(function* test() { }); //=> true
RA.isGeneratorFunction(null); //=> false
RA.isGeneratorFunction(function test() { }); //=> false
RA.isGeneratorFunction(() => {}); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isIndexed(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type

Determine if input value is an indexed data type.

Example
RA.isIndexed([1]) //=> true
RA.isIndexed('test') //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isInteger(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is an integer.

Example
RA.isInteger(0); //=> true
RA.isInteger(1); //=> true
RA.isInteger(-100000); //=> true

RA.isInteger(0.1);       //=> false
RA.isInteger(Math.PI);   //=> false

RA.isInteger(NaN);       //=> false
RA.isInteger(Infinity);  //=> false
RA.isInteger(-Infinity); //=> false
RA.isInteger('10');      //=> false
RA.isInteger(true);      //=> false
RA.isInteger(false);     //=> false
RA.isInteger([1]);       //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isIterable(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is iterable.

Example
RA.isIterable(['arrays', 'are', 'iterable']); //=> true
RA.isIterable('strings are iterable, too'); //=> true
RA.isIterable((function* () {})()); //=> true (generator objects are both iterable and iterators)

RA.isIterable({}); //=> false
RA.isIterable(-0); //=> false
RA.isIterable(null); //=> false
RA.isIterable(undefined); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isMap(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Predicate for determining if a provided value is an instance of a Map.

Example
RA.isMap(new Map()); //=> true
RA.isMap(new Map([[1, 2], [2, 1]])); //=> true
RA.isSet(new Set()); //=> false
RA.isSet(new Set([1,2]); //=> false
RA.isSet(new Object()); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNaN(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is NaN and its type is Number. It is a more robust version of the original, global isNaN().

Example
RA.isNaN(NaN); // => true
RA.isNaN(Number.NaN); // => true
RA.isNaN(0 / 0); // => true

// e.g. these would have been true with global isNaN().
RA.isNaN('NaN'); // => false
RA.isNaN(undefined); // => false
RA.isNaN({}); // => false
RA.isNaN('blabla'); // => false

RA.isNaN(true); // => false
RA.isNaN(null); // => false
RA.isNaN(37); // => false
RA.isNaN('37'); // => false
RA.isNaN('37.37'); // => false
RA.isNaN(''); // => false
RA.isNaN(' '); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNegative(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a negative Number primitive or object. Zero is not considered neither positive or negative.

Example
RA.isNegative(-1); // => true
RA.isNegative(Number.MIN_VALUE); // => false
RA.isNegative(+Infinity); // => false
RA.isNegative(NaN); // => false
RA.isNegative('5'); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNegativeZero(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a negative zero (-0).

Example
RA.isNegativeZero(-0); //=> true
RA.isNegativeZero(+0); //=> false
RA.isNegativeZero(0); //=> false
RA.isNegativeZero(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNilOrEmpty(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Returns true if the given value is its type's empty value, null or undefined.

Example
RA.isNilOrEmpty([1, 2, 3]); //=> false
RA.isNilOrEmpty([]); //=> true
RA.isNilOrEmpty(''); //=> true
RA.isNilOrEmpty(null); //=> true
RA.isNilOrEmpty(undefined): //=> true
RA.isNilOrEmpty({}); //=> true
RA.isNilOrEmpty({length: 0}); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNonEmptyArray(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is not an empty Array.

Example
RA.isNonEmptyArray([42]); // => true
RA.isNonEmptyArray([]); // => false
RA.isNonEmptyArray({}); // => false
RA.isNonEmptyArray(null); // => false
RA.isNonEmptyArray(undefined); // => false
RA.isNonEmptyArray(42); // => false
RA.isNonEmptyArray('42'); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNonEmptyString(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is not an empty String.

Example
RA.isNonEmptyString('42'); // => true
RA.isNonEmptyString(''); // => false
RA.isNonEmptyString(new String('42')); // => false
RA.isNonEmptyString(new String('')); // => false
RA.isNonEmptyString([42]); // => false
RA.isNonEmptyString({}); // => false
RA.isNonEmptyString(null); // => false
RA.isNonEmptyString(undefined); // => false
RA.isNonEmptyString(42); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNonNegative(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a non-negative Number primitive or object. This includes all positive numbers and zero.

Example
RA.isNonNegative(0); // => true
RA.isNonNegative(1); // => true
RA.isNonNegative(Infinity); // => true
RA.isNonNegative(Number.MAX_VALUE); // => true

RA.isNonNegative(-Infinity); // => false
RA.isNonNegative(Number.MIN_VALUE); // => false
RA.isNonNegative(NaN); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNonPositive(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a non-positive Number primitive or object. This includes all negative numbers and zero.

Example
RA.isNonPositive(0); // => true
RA.isNonPositive(-1); // => true
RA.isNonPositive(-Infinity); // => true
RA.isNonPositive(Number.MIN_VALUE); // => true

RA.isNonPositive(Infinity); // => false
RA.isNonPositive(Number.MAX_VALUE); // => false
RA.isNonPositive(NaN); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotArray(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of Array

Example
RA.isNotArray([]); //=> false
RA.isNotArray(null); //=> true
RA.isNotArray({}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotArrayLike(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Tests whether or not an object is similar to an array.

Example
RA.isNotArrayLike([]); //=> false
RA.isNotArrayLike(true); //=> true
RA.isNotArrayLike({}); //=> true
RA.isNotArrayLike({length: 10}); //=> true
RA.isNotArrayLike({0: 'zero', 9: 'nine', length: 10}); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotAsyncFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of Async Function

Example
RA.isNotAsyncFunction(async function test() { }); //=> false
RA.isNotAsyncFunction(null); //=> true
RA.isNotAsyncFunction(function test() { }); //=> true
RA.isNotAsyncFunction(() => {}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotBoolean(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of Boolean.

Example
RA.isNotBoolean(false); //=> false
RA.isNotBoolean(true); //=> false
RA.isNotBoolean(null); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotDate(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is complement of Date object.

Example
RA.isNotDate(new Date()); //=> false
RA.isNotDate('1997-07-16T19:20+01:00'); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotEmpty(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Logic
See also:

Returns true if the given value is not its type's empty value; false otherwise.

Example
RA.isNotEmpty([1, 2, 3]); //=> true
RA.isNotEmpty([]); //=> false
RA.isNotEmpty(''); //=> false
RA.isNotEmpty(null); //=> true
RA.isNotEmpty(undefined): //=> true
RA.isNotEmpty({}); //=> false
RA.isNotEmpty({length: 0}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotFinite(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is complement of finite Number.

Example
RA.isNotFinite(Infinity); //=> true
RA.isNotFinite(NaN); //=> true
RA.isNotFinite(-Infinity); //=> true

RA.isNotFinite(0); // false
RA.isNotFinite(2e64); // false

RA.isNotFinite('0');  // => true
RA.isNotFinite(null); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotFloat(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is complement of a float.

Example
RA.isNotFloat(0); //=> true
RA.isNotFloat(1); //=> true
RA.isNotFloat(-100000); //=> true

RA.isNotFloat(0.1);       //=> false
RA.isNotFloat(Math.PI);   //=> false

RA.isNotFloat(NaN);       //=> true
RA.isNotFloat(Infinity);  //=> true
RA.isNotFloat(-Infinity); //=> true
RA.isNotFloat('10');      //=> true
RA.isNotFloat(true);      //=> true
RA.isNotFloat(false);     //=> true
RA.isNotFloat([1]);       //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of Function.

Example
RA.isNotFunction(function test() { }); //=> false
RA.isNotFunction(function* test() { }); //=> false
RA.isNotFunction(async function test() { }); //=> false
RA.isNotFunction(() => {}); //=> false
RA.isNotFunction(null); //=> true
RA.isNotFunction('abc'); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotGeneratorFunction(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of Generator Function

Example
RA.isNotGeneratorFunction(function* test() { }); //=> false
RA.isNotGeneratorFunction(null); //=> true
RA.isNotGeneratorFunction(function test() { }); //=> true
RA.isNotGeneratorFunction(() => {}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotInteger(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is complement of an integer.

Example
RA.isNotInteger(0); //=> false
RA.isNotInteger(1); //=> false
RA.isNotInteger(-100000); //=> false

RA.isNotInteger(0.1);       //=> true
RA.isNotInteger(Math.PI);   //=> true

RA.isNotInteger(NaN);       //=> true
RA.isNotInteger(Infinity);  //=> true
RA.isNotInteger(-Infinity); //=> true
RA.isNotInteger('10');      //=> true
RA.isNotInteger(true);      //=> true
RA.isNotInteger(false);     //=> true
RA.isNotInteger([1]);       //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotMap(val) → {boolean}

Source:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is complement of Map object.

Example
RA.isNotMap(new Map()); //=> false
RA.isNotMap(new Map([[1, 2], [2, 1]])); //=> false
RA.isNotMap(new Set()); //=> true
RA.isNotMap({}); //=> true
RA.isNotMap(12); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotNaN(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks whether the passed value is complement of NaN and its type is not Number.

Example
RA.isNotNaN(NaN); // => false
RA.isNotNaN(Number.NaN); // => false
RA.isNotNaN(0 / 0); // => false

RA.isNotNaN('NaN'); // => true
RA.isNotNaN(undefined); // => true
RA.isNotNaN({}); // => true
RA.isNotNaN('blabla'); // => true

RA.isNotNaN(true); // => true
RA.isNotNaN(null); // => true
RA.isNotNaN(37); // => true
RA.isNotNaN('37'); // => true
RA.isNotNaN('37.37'); // => true
RA.isNotNaN(''); // => true
RA.isNotNaN(' '); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotNil(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of null or undefined.

Example
RA.isNotNil(null); //=> false
RA.isNotNil(undefined); //=> false
RA.isNotNil(0); //=> true
RA.isNotNil([]); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotNilOrEmpty(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Returns true if the given value is its type's empty value, null or undefined.

Example
RA.isNotNilOrEmpty([1, 2, 3]); //=> true
RA.isNotNilOrEmpty([]); //=> false
RA.isNotNilOrEmpty(''); //=> false
RA.isNotNilOrEmpty(null); //=> false
RA.isNotNilOrEmpty(undefined): //=> false
RA.isNotNilOrEmpty({}); //=> false
RA.isNotNilOrEmpty({length: 0}); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotNull(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of null.

Example
RA.isNotNull(1); //=> true
RA.isNotNull(undefined); //=> true
RA.isNotNull(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotNumber(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a complement of Number primitive or object.

Example
RA.isNotNumber(5); // => false
RA.isNotNumber(Number.MAX_VALUE); // => false
RA.isNotNumber(-Infinity); // => false
RA.isNotNumber('5'); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotObj(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isNotObject
Category:
  • Type
See also:

Checks if input value is complement of language type of Object.

Example
RA.isNotObj({}); //=> false
RA.isNotObj([]); //=> false
RA.isNotObj(() => {}); //=> false
RA.isNotObj(null); //=> true
RA.isNotObj(undefined); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotObjLike(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isNotObjectLike
Category:
  • Type
See also:

Checks if value is not object-like. A value is object-like if it's not null and has a typeof result of "object".

Example
RA.isNotObjLike({}); //=> false
RA.isNotObjLike([]); //=> false
RA.isNotObjLike(() => {}); //=> true
RA.isNotObjLike(null); //=> true
RA.isNotObjLike(undefined); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotPair(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of a pair.

Example
RA.isNotPair([]); // => true
RA.isNotPair([0]); // => true
RA.isNotPair([0, 1]); // => false
RA.isNotPair([0, 1, 2]); // => true
RA.isNotPair({0: 0, 1: 1}); // => true
RA.isNotPair({foo: 0, bar: 0}); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotPlainObj(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isNotPlainObject
Category:
  • Type
See also:

Check to see if an object is a not plain object (created using {}, new Object() or Object.create(null)).

Example
class Bar {
  constructor() {
    this.prop = 'value';
  }
}

RA.isNotPlainObj(new Bar()); //=> true
RA.isNotPlainObj({ prop: 'value' }); //=> false
RA.isNotPlainObj(['a', 'b', 'c']); //=> true
RA.isNotPlainObj(Object.create(null); //=> false
RA.isNotPlainObj(new Object()); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotRegExp(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is complement of RegExp object.

Example
RA.isNotRegExp(1); //=> true
RA.isNotRegExp(/(?:)/); //=> false
RA.isNotRegExp(new RegExp()); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotSet(val) → {boolean}

Source:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is complement of Set object.

Example
RA.isNotSet(new Map()); //=> true
RA.isNotSet(new Set()); //=> false
RA.isNotSet(new Set([1,2]); //=> false
RA.isNotSet(new Object()); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotString(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement of String.

Example
RA.isNotString('abc'); //=> false
RA.isNotString(1); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotUndefined(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is complement undefined.

Example
RA.isNotUndefined(1); //=> true
RA.isNotUndefined(undefined); //=> false
RA.isNotUndefined(null); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotValidDate(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isInvalidDate
Category:
  • Type
See also:

Checks if value is complement of valid Date object.

Example
RA.isNotValidDate(new Date()); //=> false
RA.isNotValidDate(new Date('a')); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNotValidNumber(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is not a valid Number. A valid Number is a number that is not NaN, Infinity or -Infinity.

Example
RA.isNotValidNumber(1); //=> false
RA.isNotValidNumber(''); //=> true
RA.isNotValidNumber(NaN); //=> true
RA.isNotValidNumber(Infinity); //=> true
RA.isNotValidNumber(-Infinity); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNull(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is null.

Example
RA.isNull(1); //=> false
RA.isNull(undefined); //=> false
RA.isNull(null); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isNumber(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a Number primitive or object.

Example
RA.isNumber(5); // => true
RA.isNumber(Number.MAX_VALUE); // => true
RA.isNumber(-Infinity); // => true
RA.isNumber(NaN); // => true
RA.isNumber('5'); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isObj(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isObject
Category:
  • Type
See also:

Checks if input value is language type of Object.

Example
RA.isObj({}); //=> true
RA.isObj([]); //=> true
RA.isObj(() => {}); //=> true
RA.isObj(null); //=> false
RA.isObj(undefined); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isObjLike(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isObjectLike
Category:
  • Type
See also:

Checks if value is object-like. A value is object-like if it's not null and has a typeof result of "object".

Example
RA.isObjLike({}); //=> true
RA.isObjLike([]); //=> true
RA.isObjLike(() => {}); //=> false
RA.isObjLike(null); //=> false
RA.isObjLike(undefined); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isOdd(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is odd integer number. An odd number is an integer which is not a multiple DIVISIBLE of two.

Example
RA.isOdd(1); // => true
RA.isOdd(-Infinity); // => false
RA.isOdd(4); // => false
RA.isOdd(3); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isPair(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is a pair.

Example
RA.isPair([]); // => false
RA.isPair([0]); // => false
RA.isPair([0, 1]); // => true
RA.isPair([0, 1, 2]); // => false
RA.isPair({ 0: 0, 1: 1 }); // => false
RA.isPair({ foo: 0, bar: 0 }); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isPlainObj(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Aliases:
  • isPlainObject
Category:
  • Type
See also:

Check to see if an object is a plain object (created using {}, new Object() or Object.create(null)).

Example
class Bar {
  constructor() {
    this.prop = 'value';
  }
}

RA.isPlainObj(new Bar()); //=> false
RA.isPlainObj({ prop: 'value' }); //=> true
RA.isPlainObj(['a', 'b', 'c']); //=> false
RA.isPlainObj(Object.create(null); //=> true
RA.isPlainObj(new Object()); //=> true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isPositive(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a positive Number primitive or object. Zero is not considered positive.

Example
RA.isPositive(1); // => true
RA.isPositive(Number.MAX_VALUE); // => true
RA.isPositive(-Infinity); // => false
RA.isPositive(NaN); // => false
RA.isPositive('5'); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isPositiveZero(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a positive zero (+0).

Example
RA.isPositiveZero(+0); //=> true
RA.isPositiveZero(0); //=> true
RA.isPositiveZero(-0); //=> false
RA.isPositiveZero(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isPromise(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is a native Promise. The Promise object represents the eventual completion (or failure) of an asynchronous operation, and its resulting value.

Example
RA.isPromise(null); // => false
RA.isPromise(undefined); // => false
RA.isPromise([]); // => false
RA.isPromise(Promise.resolve()); // => true
RA.isPromise(Promise.reject()); // => true
RA.isPromise({ then: () => 1 }); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isRegExp(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is RegExp object.

Example
RA.isRegExp(new RegExp()); //=> true
RA.isRegExp(/(?:)/); //=> true
RA.isRegExp(1); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isSafeInteger(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type

Checks whether the passed value is a safe integer.

Example
RA.isSafeInteger(3); //=> true
RA.isSafeInteger(Math.pow(2, 53)) //=> false
RA.isSafeInteger(Math.pow(2, 53) - 1); //=> true
RA.isSafeInteger(NaN); //=> false
RA.isSafeInteger(Infinity); //=> false
RA.isSafeInteger('3') //=> false
RA.isSafeInteger(3.1); //=> false
RA.isSafeInteger(3.0); //=> true
RA.isSafeInteger('string'); //=> false
RA.isSafeInteger(null); //=> false
RA.isSafeInteger(undefined); //=> false
RA.isSafeInteger({}); //=> false
RA.isSafeInteger(() => { }); //=> false
RA.isSafeInteger(true); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isSet(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Predicate for determining if a provided value is an instance of a Set.

Example
RA.isSet(new Map()); //=> false
RA.isSet(new Set()); //=> true
RA.isSet(new Set([1,2]); //=> true
RA.isSet(new Object()); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isSparseArray(list) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is a sparse Array. An array with at least one "empty slot" in it is often called a "sparse array." Empty slot doesn't mean that the slot contains null or undefined values, but rather that the slots don't exist.

Example
RA.isSparseArray(new Array(3)); // => true
RA.isSparseArray([1,,3]); // => true

const list = [1, 2, 3];
delete list[1];
RA.isSparseArray(list); // => true

RA.isSparseArray([1, 2, 3]); // => false
Parameters:
Name Type Description
list *

The list to test
Returns:
Type
boolean

(static) isString(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is String.

Example
RA.isString('abc'); //=> true
RA.isString(1); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isSymbol(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is a Symbol.

Example
RA.isSymbol(Symbol('1')); //=> true
RA.isSymbol(Symbol(1)); //=> true
RA.isSymbol('string'); //=> false
RA.isSymbol(undefined); //=> false
RA.isSymbol(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isThenable(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is a thenable. thenable is an object or function that defines a then method.

Example
RA.isThenable(null); // => false
RA.isThenable(undefined); // => false
RA.isThenable([]); // => false
RA.isThenable(Promise.resolve()); // => true
RA.isThenable(Promise.reject()); // => true
RA.isThenable({ then: () => 1 }); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isTrue(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is the Boolean primitive true. Will return false for Boolean objects created using the Boolean function as a constructor.

Example
RA.isTrue(true); // => true
RA.isTrue(Boolean(true)); // => true
RA.isTrue(false); // => false
RA.isTrue(1); // => false
RA.isTrue('true'); // => false
RA.isTrue(new Boolean(true)); // => false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isTruthy(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

In JavaScript, a truthy value is a value that is considered true when evaluated in a Boolean context. All values are truthy unless they are defined as falsy (i.e., except for false, 0, "", null, undefined, and NaN).

Example
RA.isTruthy({}); // => true
RA.isTruthy([]); // => true
RA.isTruthy(42); // => true
RA.isTruthy(3.14); // => true
RA.isTruthy('foo'); // => true
RA.isTruthy(new Date()); // => true
RA.isTruthy(Infinity); // => true
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isUndefined(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if input value is undefined.

Example
RA.isUndefined(1); //=> false
RA.isUndefined(undefined); //=> true
RA.isUndefined(null); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isValidDate(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is valid Date object.

Example
RA.isValidDate(new Date()); //=> true
RA.isValidDate(new Date('a')); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) isValidNumber(val) → {boolean}

Source:
Since:
Signature:
  • * -> Boolean
Category:
  • Type
See also:

Checks if value is a valid Number. A valid Number is a number that is not NaN, Infinity or -Infinity.

Example
RA.isValidNumber(1); //=> true
RA.isValidNumber(''); //=> false
RA.isValidNumber(NaN); //=> false
RA.isValidNumber(Infinity); //=> false
RA.isValidNumber(-Infinity); //=> false
Parameters:
Name Type Description
val *

The value to test
Returns:
Type
boolean

(static) lastP(iterable) → {Promise}

Source:
Since:
Signature:
  • [Promise a] -> Promise a
Category:
  • Function
See also:

Returns a promise that is fulfilled by the last given promise to be fulfilled, or rejected with an array of rejection reasons if all of the given promises are rejected.

Example
const delayP = timeout => new Promise(resolve => setTimeout(() => resolve(timeout), timeout));
delayP.reject = timeout => new Promise((resolve, reject) => setTimeout(() => reject(timeout), timeout));
RA.lastP([
  1,
  delayP(10),
  delayP(100),
  delayP.reject(1000),
]); //=> Promise(100)
Parameters:
Name Type Description
iterable Iterable.<*>

An iterable object such as an Array or String
Returns:

A promise that is fulfilled by the last given promise to be fulfilled, or rejected with an array of rejection reasons if all of the given promises are rejected.

Type
Promise

(static) lengthEq(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length equal to valueLength.

Example
RA.lengthEq(3, [1,2,3]); //=> true
RA.lengthEq(3, [1,2,3,4]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lengthGt(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length greater than valueLength.

Example
RA.lengthGt(3, [1,2,3,4]); //=> true
RA.lengthGt(3, [1,2,3]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lengthGte(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length greater than or equal to valueLength.

Example
RA.lengthGte(3, [1,2,3,4]); //=> true
RA.lengthGte(3, [1,2,3]); //=> true
RA.lengthGte(3, [1,2]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lengthLt(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length less than valueLength.

Example
RA.lengthLt(3, [1,2]); //=> true
RA.lengthLt(3, [1,2,3]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lengthLte(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length less than or equal to valueLength.

Example
RA.lengthLte(3, [1,2]); //=> true
RA.lengthLte(3, [1,2,3]); //=> true
RA.lengthLte(3, [1,2,3,4]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lengthNotEq(valueLength, value) → {boolean}

Source:
Since:
Signature:
  • Number -> [*] -> Boolean
Category:
  • List
See also:

Returns true if the supplied list or string has a length not equal to valueLength.

Example
RA.lengthNotEq(3, [1,2,3,4]); //=> true
RA.lengthNotEq(3, [1,2,3]); //=> false
Parameters:
Name Type Description
valueLength number

The length of the list or string
value Array | string

The list or string
Returns:
Type
boolean

(static) lensEq(lens, value, data) → {boolean}

Source:
Since:
Signature:
  • Lens s a -> b -> s -> Boolean
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Returns true if data structure focused by the given lens equals provided value.

Example
RA.lensEq(R.lensIndex(0), 1, [0, 1, 2]); // => false
RA.lensEq(R.lensIndex(1), 1, [0, 1, 2]); // => true
RA.lensEq(R.lensPath(['a', 'b']), 'foo', { a: { b: 'foo' } }) // => true
Parameters:
Name Type Description
lens function

Van Laarhoven lens
value *

The value to compare the focused data structure with
data *

The data structure
Returns:

true if the focused data structure equals value, false otherwise

Type
boolean

(static) lensIso(tonon-null, fromnon-null) → (non-null) {function}

Source:
Since:
Signature:
  • (s -> a) -> (a -> s) -> Lens s a
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Defines an isomorphism that will work like a lens. It takes two functions. The function that converts and the function that recovers.

Example
const lensJSON = RA.lensIso(JSON.parse, JSON.stringify);

R.over(lensJSON, assoc('b', 2), '{"a":1}'); //=> '{"a":1,"b":2}'
R.over(RA.lensIso.from(lensJSON), R.replace('}', ',"b":2}'), { a: 1 }); // => { a: 1, b: 2 }
Parameters:
Name Type Description
to function

The function that converts
from function

The function that recovers
Returns:

The isomorphic lens

Type
function

(static) lensNotEq(lens, value, data) → {boolean}

Source:
Since:
Signature:
  • Lens s a -> b -> s -> Boolean
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Returns true if data structure focused by the given lens doesn't equal provided value.

Example
RA.lensNotEq(R.lensIndex(0), 1, [0, 1, 2]); // => true
RA.lensNotEq(R.lensIndex(1), 1, [0, 1, 2]); // => false
RA.lensNotEq(R.lensPath(['a', 'b']), 'foo', { a: { b: 'foo' } }) // => false
Parameters:
Name Type Description
lens function

Van Laarhoven lens
value *

The value to compare the focused data structure with
data *

The data structure
Returns:

false if the focused data structure equals value, true otherwise

Type
boolean

(static) lensNotSatisfy(predicate, lens, data) → {boolean}

Source:
Since:
Signature:
  • Boolean b => (a -> b) -> Lens s a -> s -> b
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Returns true if data structure focused by the given lens doesn't satisfy the predicate. Note that the predicate is expected to return boolean value.

Example
RA.lensNotSatisfy(RA.isTrue, R.lensIndex(0), [false, true, 1]); // => true
RA.lensNotSatisfy(RA.isTrue, R.lensIndex(1), [false, true, 1]); // => false
RA.lensNotSatisfy(RA.isTrue, R.lensIndex(2), [false, true, 1]); // => true
RA.lensNotSatisfy(R.identity, R.lensProp('x'), { x: 1 }); // => true
Parameters:
Name Type Description
predicate function

The predicate function
lens function

Van Laarhoven lens
data *

The data structure
Returns:

false if the focused data structure satisfies the predicate, true otherwise

Type
boolean

(static) lensSatisfies(predicate, lens, data) → {boolean}

Source:
Since:
Signature:
  • Boolean b => (a -> b) -> Lens s a -> s -> b
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Returns true if data structure focused by the given lens satisfies the predicate. Note that the predicate is expected to return boolean value and will be evaluated as false unless the predicate returns true.

Example
RA.lensSatisfies(RA.isTrue, R.lensIndex(0), [false, true, 1]); // => false
RA.lensSatisfies(RA.isTrue, R.lensIndex(1), [false, true, 1]); // => true
RA.lensSatisfies(RA.isTrue, R.lensIndex(2), [false, true, 1]); // => false
RA.lensSatisfies(R.identity, R.lensProp('x'), { x: 1 }); // => false
Parameters:
Name Type Description
predicate function

The predicate function
lens function

Van Laarhoven lens
data *

The data structure
Returns:

true if the focused data structure satisfies the predicate, false otherwise

Type
boolean

(static) lensTraverse(ofnon-null) → (non-null) {function}

Source:
Since:
Signature:
  • Applicative f => (a -> f a) -> Lens s a
  • Lens s a = Functor f => (a -> f a) -> s -> f s
Category:
  • Relation
See also:

Creates a Traversable lens from an Applicative-returning function.

When executed, it maps an Applicative-returning function over a Traversable, then uses sequence to transform the resulting Traversable of Applicative into an Applicative of Traversable.

Dispatches to the traverse method of the third argument, if present.

Example
const maybeLens = RA.lensTraverse(Maybe.of);
const safeDiv = n => d => d === 0 ? Maybe.Nothing() : Maybe.Just(n / d)

R.over(maybeLens, safeDiv(10), [2, 4, 5]); // => Just([5, 2.5, 2])
R.over(maybeLens, safeDiv(10), [2, 0, 5]); // => Nothing

R.view(maybeLens, [Maybe.Just(2), Maybe.Just(3)]); // => Maybe.Just([2, 3])

R.set(maybeLens, Maybe.Just(1), [Maybe.just(2), Maybe.Just(3)]); // => Maybe.Just([1, 1])
Parameters:
Name Type Description
of function

The Applicative-returning function
Returns:

The Traversable lens

Type
function

(static) liftF(fn) → {function}

Source:
Since:
Signature:
  • Apply a => (a... -> a) -> (a... -> a)
Category:
  • Function
See also:

"lifts" a function to be the specified arity, so that it may "map over" objects that satisfy the fantasy land Apply spec of algebraic structures.

Lifting is specific for scalaz and function Java implementations. Old version of fantasy land spec were not compatible with this approach, but as of fantasy land 1.0.0 Apply spec also adopted this approach.

This function acts as interop for ramda <= 0.23.0 and monet.js.

More info here.

Example
const { Maybe } = require('monet');

const add3 = (a, b, c) => a + b + c;
const madd3 = RA.liftF(add3);

madd3(Maybe.Some(10), Maybe.Some(15), Maybe.Some(17)); //=> Maybe.Some(42)
madd3(Maybe.Some(10), Maybe.Nothing(), Maybe.Some(17)); //=> Maybe.Nothing()
Parameters:
Name Type Description
fn function

The function to lift into higher context
Returns:

The lifted function

Type
function

(static) liftFN(arity, fn) → {function}

Source:
Since:
Signature:
  • Apply a => Number -> (a... -> a) -> (a... -> a)
Category:
  • Function
See also:

"lifts" a function to be the specified arity, so that it may "map over" objects that satisfy the fantasy land Apply spec of algebraic structures.

Lifting is specific for scalaz and functional java implementations. Old version of fantasy land spec were not compatible with this approach, but as of fantasy land 1.0.0 Apply spec also adopted this approach.

This function acts as interop for ramda <= 0.23.0 and monet.js.

More info here.

Example
const { Maybe } = require('monet');

const add3 = (a, b, c) => a + b + c;
const madd3 = RA.liftFN(3, add3);

madd3(Maybe.Some(10), Maybe.Some(15), Maybe.Some(17)); //=> Maybe.Some(42)
madd3(Maybe.Some(10), Maybe.Nothing(), Maybe.Some(17)); //=> Maybe.Nothing()
Parameters:
Name Type Description
arity Number

The arity of the lifter function
fn function

The function to lift into higher context
Returns:

The lifted function

Type
function

(static) list(…items) → {Array}

Source:
Since:
Signature:
  • a... -> [a...]
Category:
  • List
See also:

Creates a list from arguments.

Example
RA.list('a', 'b', 'c'); //=> ['a', 'b', 'c']
Parameters:
Name Type Attributes Description
items * <repeatable>

The items of the feature list
Returns:

New list created from items

Type
Array

(static) makeFlat(=non-null, =non-null) → (non-null) {Array}

Source:
Signature:
  • Bool -> List -> List
Category:
  • List

makeFlat is a helper function that returns a one-level or fully recursive function based on the flag passed in.

Parameters:
Name Type Description
= bool

should recursively flatten
= Array

the nested list to be flattened
Returns:

= the flattened list

Type
Array

(static) mapIndexed(fn, list) → {Array}

Source:
Since:
Signature:
  • Functor f => ((a, Idx, f a) => b) => f a -> f b
  • Idx = Number
Category:
  • List
See also:

R.map function that more closely resembles Array.prototype.map. It takes two new parameters to its callback function: the current index, and the entire list.

mapIndexed implementation is simple : const mapIndexed = R.addIndex(R.map);

Example
RA.mapIndexed((val, idx, list) => idx + '-' + val, ['f', 'o', 'o', 'b', 'a', 'r']);
//=> ['0-f', '1-o', '2-o', '3-b', '4-a', '5-r']
Parameters:
Name Type Description
fn function

The function to be called on every element of the input list
list Array

The list to be iterated over
Returns:

The new list

Type
Array

(static) mergePath(pathnon-null, sourcenon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [k] -> {a} -> {k: {a}} -> {k: {a}}
Category:
  • Object
See also:

Create a new object with the own properties of the object under the path merged with the own properties of the provided source. If a key exists in both objects, the value from the source object will be used.

Example
RA.mergePath(
 ['outer', 'inner'],
 { foo: 3, bar: 4 },
 { outer: { inner: { foo: 2 } } }
); //=> { outer: { inner: { foo: 3, bar: 4 } }
Parameters:
Name Type Description
path Array

The property path of the destination object
source Object

The source object
obj Object

The object that has destination object under corresponding property path
Returns:

The new version of object

Type
Object

(static) mergePaths(pathsnon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [[k]] -> {k: {a}} -> {a}
Category:
  • Object
See also:

Merge objects under corresponding paths.

Example
const obj = {
  foo: { fooInner: { fooInner2: 1 } },
  bar: { barInner: 2 }
};

{ ...obj.foo.fooInner, ...obj.bar }; //=>  { fooInner2: 1, barInner: 2 }
RA.mergePaths([['foo', 'fooInner'], ['bar']], obj); //=> { fooInner2: 1, barInner: 2 }
Parameters:
Name Type Description
paths Array

The property paths to merge
obj Object

The object to query
Returns:

The object composed of merged property paths of obj

Type
Object

(static) mergeProp(pnon-null, sourcenon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [k] -> {a} -> {k: {a}} -> {k: {a}}
Category:
  • Object
See also:

Create a new object with the own properties of the object under the p merged with the own properties of the provided source. If a key exists in both objects, the value from the source object will be used.

Example
RA.mergeProp(
 'outer',
 { foo: 3, bar: 4 },
 { outer: { foo: 2 } }
); //=> { outer: { foo: 3, bar: 4 } };
Parameters:
Name Type Description
p Array

The property of the destination object
source Object

The source object
obj Object

The object that has destination object under corresponding property
Returns:

The new version of object

Type
Object

(static) mergeProps(psnon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [k] -> {k: {a}} -> {a}
Category:
  • Object
See also:

Functional equivalent of merging object properties with object spread operator.

Example
const obj = {
  foo: { fooInner: 1 },
  bar: { barInner: 2 }
};

{ ...obj.foo, ...obj.bar }; //=> { fooInner: 1, barInner: 2 }
RA.mergeProps(['foo', 'bar'], obj); //=> { fooInner: 1, barInner: 2 }
Parameters:
Name Type Description
ps Array

The property names to merge
obj Object

The object to query
Returns:

The object composed of merged properties of obj

Type
Object

(static) mergeRight(r, l) → {Object}

Source:
Since:
Deprecated:
  • since v2.12.0; available in ramda@0.26.0 as R.mergeLeft
Signature:
  • {k: v} -> {k: v} -> {k: v}
Aliases:
  • mergeLeft, resetToDefault
Category:
  • Object
See also:

Create a new object with the own properties of the second object merged with the own properties of the first object. If a key exists in both objects, the value from the first object will be used. * Putting it simply: it sets properties only if they don't exist.

Example
RA.mergeRight({ 'age': 40 }, { 'name': 'fred', 'age': 10 });
//=> { 'name': 'fred', 'age': 40 }
Parameters:
Name Type Description
r Object

Destination
l Object

Source
Returns:
Type
Object

(static) move(fromIdx, toIdx, list) → {Array}

Source:
Since:
Signature:
  • Number -> Number -> [a] -> [a]
Category:
  • List

Returns a new list with the item at the position fromIdx moved to the position toIdx. If the toIdx is out of the list range, the item will be placed at the last position of the list. When negative indices are provided, the behavior of the move is unspecified.

Example
const list = ['a', 'b', 'c', 'd', 'e'];
RA.move(1, 3, list) //=> ['a', 'c', 'd', 'b', 'e']
Parameters:
Name Type Description
fromIdx Number

The position of item to be moved
toIdx Number

The position of item after move
list Array

The list containing the item to be moved
Returns:
Type
Array

(static) nand(a, b) → {Boolean}

Source:
Since:
Signature:
  • a -> b -> Boolean
Category:
  • Logic

Returns false if both arguments are truthy; true otherwise.

Example
RA.nand(true, true); //=> false
RA.nand(false, true); //=> true
RA.nand(true, false); //=> true
RA.nand(false, false); //=> true
RA.nand(1.0, 1.0); //=> false
RA.nand(1.0, 0); //=> true
RA.nand(0, 1.0); //=> true
RA.nand(0, 0); //=> true
Parameters:
Name Type Description
a *
b *
Returns:

false if both arguments are truesy

Type
Boolean

(static) neither(f, g) → {function}

Source:
Since:
Signature:
  • (*... -> Boolean) -> (*... -> Boolean) -> (*... -> Boolean)
Category:
  • Logic
See also:

A function which calls the two provided functions and returns the complement of ||ing the results. It returns false if the first function is truth-y and the complement of the second function otherwise. Note that this is short-circuited, meaning that the second function will not be invoked if the first returns a truth-y value. In short it will return true if neither predicate returns true.

In addition to functions, RA.neither also accepts any fantasy-land compatible applicative functor.

Example
const gt10 = R.gt(R.__, 10)
const even = (x) => x % 2 === 0;
const f = RA.neither(gt10, even);

f(12); //=> false
f(8); //=> false
f(11); //=> false
f(9); //=> true
Parameters:
Name Type Description
f function

A predicate
g function

Another predicate
Returns:

Returns a function that applies its arguments to f and g and returns the complement of ||ing their outputs together.

Type
function

(static) noneP(iterable) → {Promise}

Source:
Since:
Signature:
  • [Promise a] -> Promise [a]
Category:
  • Function
See also:

Returns a Promise that is resolved with an array of reasons when all of the provided Promises reject, or rejected when any Promise is resolved. This pattern is like allP, but fulfillments and rejections are transposed - rejections become the fulfillment values and vice versa.

Example
RA.noneP([Promise.reject('hello'), Promise.reject('world')]); //=> Promise(['hello', 'world'])
RA.noneP([]); //=> Promise([])
RA.noneP([Promise.reject(), Promise.resolve('hello world')]); //=> Promise('hello world')
RA.noneP([Promise.reject(), 'hello world']); //=> Promise('hello world')
Parameters:
Name Type Description
iterable Iterable.<*>

An iterable object such as an Array or String
Returns:

A Promise that is resolved with a list of rejection reasons if all Promises are rejected, or a Promise that is rejected with the fulfillment value of the first Promise that resolves.

Type
Promise

(static) nonePass(predicates) → {function}

Source:
Since:
Signature:
  • [(*... -> Boolean)] -> (*... -> Boolean)
Category:
  • Logic
See also:

Takes a list of predicates and returns a predicate that returns true for a given list of arguments if none of the provided predicates are satisfied by those arguments. It is the complement of Ramda's anyPass.

The function returned is a curried function whose arity matches that of the highest-arity predicate.

Example
const gt10 = R.gt(R.__, 10)
const even = (x) => x % 2 === 0;
const f = RA.nonePass([gt10, even]);

f(12); //=> false
f(8); //=> false
f(11); //=> false
f(9); //=> true
Parameters:
Name Type Description
predicates Array

An array of predicates to check
Returns:

The combined predicate

Type
function

(static) noop() → {undefined}

Source:
Since:
Signature:
  • ... -> undefined
Category:
  • Function

A function that performs no operations.

Example
RA.noop(); //=> undefined
RA.noop(1, 2, 3); //=> undefined
Returns:
Type
undefined

(static) nor(a, b) → {boolean}

Source:
Since:
Signature:
  • a -> b -> a ⊽ b
Category:
  • Logic
See also:

Returns true if both arguments are falsy; false otherwise.

Example
RA.nor(true, true); //=> false
RA.nor(false, true); //=> false
RA.nor(true, false); //=> false
RA.nor(false, false); //=> true
RA.nor(1, 1); //=> false
RA.nor(1, 0); //=> false
RA.nor(0, 1); //=> false
RA.nor(0, 0); //=> true
Parameters:
Name Type Description
a *
b *
Returns:

true if both arguments are falsy

Type
boolean

(static) notAllPass(predicates) → {function}

Source:
Since:
Signature:
  • [(*... -> Boolean)] -> (*... -> Boolean)
Category:
  • Logic
See also:

Takes a list of predicates and returns a predicate that returns true for a given list of arguments if one or more of the provided predicates is not satisfied by those arguments. It is the complement of Ramda's allPass.

The function returned is a curried function whose arity matches that of the highest-arity predicate.

Example
const gt10 = R.gt(R.__, 10)
const even = (x) => x % 2 === 0;
const f = RA.notAllPass([gt10, even]);

f(12); //=> false
f(8); //=> true
f(11); //=> true
f(9); //=> true
Parameters:
Name Type Description
predicates Array

An array of predicates to check
Returns:

The combined predicate

Type
function

(static) notAllUnique(list) → {boolean}

Source:
Since:
Signature:
  • [a] -> Boolean
Category:
  • List
See also:

Returns true if at least one item of the list is repeated. R.equals is used to determine equality.

Example
RA.notAllUnique([ 1, 1, 2, 3 ]); //=> true
RA.notAllUnique([ 1, 2, 3, 4 ]); //=> false
RA.notAllUnique([]); //=> false
Parameters:
Name Type Description
list Array

The list of values
Returns:
Type
boolean

(static) notBoth(f, g) → {function}

Source:
Since:
Signature:
  • (*... -> Boolean) -> (*... -> Boolean) -> (*... -> Boolean)
Category:
  • Logic
See also:

A function which calls the two provided functions and returns the complement of &&ing the results. It returns true if the first function is false-y and the complement of the second function otherwise. Note that this is short-circuited, meaning that the second function will not be invoked if the first returns a false-y value. In short it will return true unless both predicates return true.

In addition to functions, RA.notBoth also accepts any fantasy-land compatible applicative functor.

Example
const gt10 = R.gt(R.__, 10)
const even = (x) => x % 2 === 0;
const f = RA.notBoth(gt10, even);

f(12); //=> false
f(8); //=> true
f(11); //=> true
f(9); //=> true
Parameters:
Name Type Description
f function

A predicate
g function

Another predicate
Returns:

Returns a function that applies its arguments to f and g and returns the complement of &&ing their outputs together.

Type
function

(static) omitBy(prednon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • ((v, k) -> Boolean) -> {k: v} -> {k: v}
Category:
  • Object

Returns a partial copy of an object containing only the keys that don't satisfy the supplied predicate.

Example
const isLowerCase = (val, key) => key.toLowerCase() === key;
RA.omitBy(isLowerCase, {a: 1, b: 2, A: 3, B: 4}); //=> {A: 3, B: 4}
Parameters:
Name Type Description
pred function

A predicate to determine whether or not a key should be included on the output object
obj Object

The object to copy from
Returns:

A new object only with properties that don't satisfy pred

Type
Object

(static) omitIndexes(indexesnon-null, listnon-null) → (non-null) {Array}

Source:
Since:
Signature:
  • [Int] -> [a] -> [a]
Category:
  • List
See also:

Returns a partial copy of an array omitting the indexes specified.

Example
RA.omitIndexes([-1, 1, 3], ['a', 'b', 'c', 'd']); //=> ['a', 'c']
Parameters:
Name Type Description
indexes Array

The array of indexes to omit from the new array
list Array

The array to copy from
Returns:

The new array with omitted indexes

Type
Array

(static) padCharsEnd(padString, targetLength, value) → {string}

Source:
Since:
Signature:
  • String -> Number -> String -> String
Category:
  • String
See also:

The function pads the current string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the end of the current string.

Example
RA.padCharsEnd('-', 3, 'a'); // => 'a--'
RA.padCharsEnd('foo', 10, 'abc'); // => 'abcfoofoof'
RA.padCharsEnd('123456', 6, 'abc'); // => 'abc123'
Parameters:
Name Type Description
padString string

The string to pad the current string with
targetLength number

The length of the resulting string once the current string has been padded
value string

String value to be padded
Returns:

A new string of the specified length with the pad string applied at the end of the current string

Type
string

(static) padCharsStart(padString, targetLength, value) → {string}

Source:
Since:
Signature:
  • String -> Number -> String -> String
Category:
  • String
See also:

The function pads the current string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the start of the current string.

Example
RA.padCharsStart('-', 3, 'a'); // => '--a'
RA.padCharsStart('foo', 10, 'abc'); // => 'foofoofabc'
RA.padCharsStart('123456', 6, 'abc'); // => '123abc'
Parameters:
Name Type Description
padString string

The string to pad the current string with
targetLength number

The length of the resulting string once the current string has been padded
value string

String value to be padded
Returns:

A new string of the specified length with the pad string on the start of current string

Type
string

(static) padEnd(targetLength, value) → {string}

Source:
Since:
Signature:
  • Number -> String -> String
Category:
  • String
See also:

The function pads the current string with an empty string so that the resulting string reaches a given length. The padding is applied from the end of the current string.

Example
RA.padEnd(3, 'a'); // => 'a  '
Parameters:
Name Type Description
targetLength number

The length of the resulting string once the current string has been padded
value string

String value to be padded
Returns:

A new string of the specified length with the pad string applied at the end of the current string

Type
string

(static) padStart(targetLength, value) → {string}

Source:
Since:
Signature:
  • Number -> String -> String
Category:
  • String
See also:

Pads string on the left side if it's shorter than length.

Example
RA.padStart(3, 'a'); // => '  a'
Parameters:
Name Type Description
targetLength number

The length of the resulting string once the current string has been padded
value string

String value to be padded
Returns:

A new string of the specified length with the empty string applied to the beginning of the current string

Type
string

(static) pathNotEq(path, val, object) → {boolean}

Source:
Since:
Signature:
  • [Idx] => a => {a} => Boolean
  • Idx = String | Int
Category:
  • Relation
See also:

Determines whether a nested path on an object doesn't have a specific value, in R.equals terms. Most likely used to filter a list.

Example
const user1 = { address: { zipCode: 90210 } };
const user2 = { address: { zipCode: 55555 } };
const user3 = { name: 'Bob' };
const users = [ user1, user2, user3 ];
const isFamous = R.pathNotEq(['address', 'zipCode'], 90210);
R.filter(isFamous, users); //=> [ user2, user3 ]
Parameters:
Name Type Description
path Array

The path of the nested property to use
val a

The value to compare the nested property with
object Object

The object to check the nested property in
Returns:

Returns Boolean false if the value equals the nested object property, true otherwise

Type
boolean

(static) pathOrLazy(defaultFn, path, obj) → {*}

Source:
Since:
Signature:
  • ({a} -> a) -> [Idx] -> {a} -> a
  • Idx = String | Int
Category:
  • Object

If the given, non-null object has a value at the given path, returns the value at that path. Otherwise returns the result of invoking the provided function with the object.

Example
RA.pathOrLazy(() => 'N/A', ['a', 'b'], {a: {b: 2}}); //=> 2
RA.pathOrLazy(() => 'N/A', ['a', 'b'], {c: {b: 2}}); //=> "N/A"
Parameters:
Name Type Description
defaultFn function

The function that will return the default value.
path Array

The path to use.
obj Object

The object to retrieve the nested property from.
Returns:

The data at path of the supplied object or the default value.

Type
*

(static) paths(ps, obj) → {Array}

Source:
Since:
Signature:
  • [[k]] -> {k: v} - [v]
Category:
  • List
See also:

Acts as multiple path: arrays of paths in, array of values out. Preserves order.

Example
const obj = {
  a: { b: { c: 1 } },
  x: 2,
};

RA.paths([['a', 'b', 'c'], ['x']], obj); //=> [1, 2]
Parameters:
Name Type Description
ps Array

The property paths to fetch
obj Object

The object to query
Returns:

The corresponding values or partially applied function

Type
Array

(static) pickIndexes(indexes, list) → {Array}

Source:
Since:
Signature:
  • [Number] -> [a] -> [a]
Category:
  • List
See also:

Picks values from list by indexes.

Note: pickIndexes will skip non existing indexes. If you want to include them use ramda's props function.

Example
RA.pickIndexes([0, 2], ['a', 'b', 'c']); //=> ['a', 'c']
Parameters:
Name Type Description
indexes Array

The indexes to pick
list Array

The list to pick values from
Returns:

New array containing only values at indexes

Type
Array

(static) propNotEq(name, val, object) → {boolean}

Source:
Since:
Signature:
  • String -> a -> Object -> Boolean
Category:
  • Relation
See also:

Returns true if the specified object property is not equal, in R.equals terms, to the given value; false otherwise.

Example
const abby = { name: 'Abby', age: 7, hair: 'blond' };
const fred = { name: 'Fred', age: 12, hair: 'brown' };
const rusty = { name: 'Rusty', age: 10, hair: 'brown' };
const alois = { name: 'Alois', age: 15, disposition: 'surly' };
const kids = [abby, fred, rusty, alois];
const hasNotBrownHair = RA.propNotEq('hair', 'brown');

R.filter(hasNotBrownHair, kids); //=> [abby, alois]
Parameters:
Name Type Description
name String

The property to pick
val a

The value to compare to
object Object

The object, that presumably contains value under the property
Returns:

Comparison result

Type
boolean

(static) reduceIndexed(fn, acc, list) → {*}

Source:
Since:
Signature:
  • ((a, b, Idx, [b]) => a) -> a -> [b] -> a
  • Idx = Number
Category:
  • List
See also:

R.reduce function that more closely resembles Array.prototype.reduce. It takes two new parameters to its callback function: the current index, and the entire list.

reduceIndexed implementation is simple : const reduceIndexed = R.addIndex(R.reduce);

Example
const initialList = ['f', 'o', 'o', 'b', 'a', 'r'];

reduceIndexed((acc, val, idx, list) => acc + '-' + val + idx, '', initialList);
//=> "-f0-o1-o2-b3-a4-r5"
Parameters:
Name Type Description
fn function

The iterator function. Receives four values, the accumulator, the current element from the array, index and the entire list
acc *

The accumulator value
list Array

The list to iterate over
Returns:

The final, accumulated value

Type
*

(static) reduceP(fn, acc, list) → {Promise}

Source:
Since:
Signature:
  • ((Promise a, MaybePromise b) -> Promise a) -> MaybePromise a -> MaybePromise [MaybePromise b] -> Promise a
  • MaybePromise = Promise.<*> | *
Category:
  • List
See also:

Given an Iterable(arrays are Iterable), or a promise of an Iterable, which produces promises (or a mix of promises and values), iterate over all the values in the Iterable into an array and reduce the array to a value using the given iterator function.

If the iterator function returns a promise, then the result of the promise is awaited, before continuing with next iteration. If any promise in the array is rejected or a promise returned by the iterator function is rejected, the result is rejected as well.

If initialValue is undefined (or a promise that resolves to undefined) and the Iterable contains only 1 item, the callback will not be called and the Iterable's single item is returned. If the Iterable is empty, the callback will not be called and initialValue is returned (which may be undefined).

This function is basically equivalent to bluebird.reduce.

Example
RA.reduceP(
  (total, fileName) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  ['file1.txt', 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceP(
  (total, fileName) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  Promise.resolve(0),
  ['file1.txt', 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceP(
  (total, fileName) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  [Promise.resolve('file1.txt'), 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceP(
  (total, fileName) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  Promise.resolve([Promise.resolve('file1.txt'), 'file2.txt', 'file3.txt'])
); // => Promise(10)
Parameters:
Name Type Description
fn function

The iterator function. Receives two values, the accumulator and the current element from the list
acc * | Promise.<*>

The accumulator value
list Array.<*> | Promise.<Array.<(*|Promise.<*>)>>

The list to iterate over
Returns:

The final, accumulated value

Type
Promise

(static) reduceRightP(fn, acc, list) → {Promise}

Source:
Since:
Signature:
  • ((MaybePromise b, Promise a) -> Promise a) -> MaybePromise a -> MaybePromise [MaybePromise b] -> Promise a
  • MaybePromise = Promise.<*> | *
Category:
  • List
See also:

Given an Iterable(arrays are Iterable), or a promise of an Iterable, which produces promises (or a mix of promises and values), iterate over all the values in the Iterable into an array and reduce the array to a value using the given iterator function.

Similar to reduceP except moves through the input list from the right to the left. The iterator function receives two values: (value, acc), while the arguments' order of reduceP's iterator function is (acc, value).

Example
RA.reduceRightP(
  (fileName, total) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  ['file1.txt', 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceRightP(
  (fileName, total) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  Promise.resolve(0),
  ['file1.txt', 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceRightP(
  (fileName, total) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  [Promise.resolve('file1.txt'), 'file2.txt', 'file3.txt']
); // => Promise(10)

RA.reduceRightP(
  (fileName, total) => fs
    .readFileAsync(fileName, 'utf8')
    .then(contents => total + parseInt(contents, 10)),
  0,
  Promise.resolve([Promise.resolve('file1.txt'), 'file2.txt', 'file3.txt'])
); // => Promise(10)
Parameters:
Name Type Description
fn function

The iterator function. Receives two values, the current element from the list and the accumulator
acc * | Promise.<*>

The accumulator value
list Array.<*> | Promise.<Array.<(*|Promise.<*>)>>

The list to iterate over
Returns:

The final, accumulated value

Type
Promise

(static) rejectP(reasonopt) → {Promise}

Source:
Since:
Signature:
  • a -> Promise a
Category:
  • Function
See also:

Composable shortcut for Promise.reject.

Returns a Promise object that is rejected with the given reason.

Example
RA.rejectP(); //=> Promise(undefined)
RA.rejectP('a'); //=> Promise('a')
RA.rejectP([1, 2, 3]); //=> Promise([1, 2, 3])
Parameters:
Name Type Attributes Description
reason * <optional>

Reason why this Promise rejected
Returns:

A Promise that is rejected with the given reason

Type
Promise

(static) renameKeys(keysMapnon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • {a: b} -> {a: *} -> {b: *}
Category:
  • Object
See also:

Creates a new object with the own properties of the provided object, but the keys renamed according to the keysMap object as {oldKey: newKey}. When some key is not found in the keysMap, then it's passed as-is.

Keep in mind that in the case of keys conflict is behaviour undefined and the result may vary between various JS engines!

Example
const input = { firstName: 'Elisia', age: 22, type: 'human' };

RA.renameKeys({ firstName: 'name', type: 'kind', foo: 'bar' })(input);
//=> { name: 'Elisia', age: 22, kind: 'human' }
Parameters:
Name Type Description
keysMap Object
obj Object
Returns:

New object with renamed keys

Type
Object

(static) renameKeysWith(fn, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • (a -> b) -> {a: *} -> {b: *}
Category:
  • Object
See also:

Creates a new object with the own properties of the provided object, but the keys renamed according to logic of renaming function.

Keep in mind that in the case of keys conflict is behaviour undefined and the result may vary between various JS engines!

Example
RA.renameKeysWith(R.concat('a'), { A: 1, B: 2, C: 3 }) //=> { aA: 1, aB: 2, aC: 3 }
Parameters:
Name Type Description
fn function

Function that renames the keys
obj Object

Provided object
Returns:

New object with renamed keys

Type
Object

(static) repeatStr(value, count) → {string}

Source:
Since:
Signature:
  • String -> Number -> String
Category:
  • List

Constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together.

Example
RA.repeatStr('a', 3); //=> 'aaa'
Parameters:
Name Type Description
value string

String value to be repeated
count number

An integer between 0 and +∞: [0, +∞), indicating the number of times to repeat the string in the newly-created string that is to be returned
Returns:

A new string containing the specified number of copies of the given string

Type
string

(static) replaceAll(searchValue, replaceValue, str) → {string}

Source:
Since:
Signature:
  • String -> String -> String -> String
Category:
  • String
See also:

Replaces all substring matches in a string with a replacement.

Example
RA.replaceAll('ac', 'ef', 'ac ab ac ab'); //=> 'ef ab ef ab'
RA.replaceAll('', '_', 'xxx'); //=> '_x_x_x_'
RA.replaceAll(/x/g, 'v', 'xxx'); //=> 'vvv'
RA.replaceAll(/x/, 'v', 'xxx'); //=> TypeError
Parameters:
Name Type Description
searchValue string

The substring or a global RegExp to match
replaceValue string

The string to replace the matches with
str string

The String to do the search and replacement in
Throws:

When invalid arguments provided

Type
TypeError
Returns:

A new string containing all the searchValue replaced with the replaceValue

Type
string

(static) resolveP(valueopt) → {Promise}

Source:
Since:
Signature:
  • a -> Promise a
Category:
  • Function
See also:

Composable shortcut for Promise.resolve.

Returns a Promise object that is resolved with the given value. If the value is a thenable (i.e. has a "then" method), the returned promise will "follow" that thenable, adopting its eventual state.

Example
RA.resolveP(); //=> Promise(undefined)
RA.resolveP('a'); //=> Promise('a')
RA.resolveP([1, 2, 3]); //=> Promise([1, 2, 3])
Parameters:
Name Type Attributes Description
value * <optional>

Argument to be resolved by this Promise. Can also be a Promise or a thenable to resolve
Returns:

A Promise that is resolved with the given value, or the promise passed as value, if the value was a promise object

Type
Promise

(static) round(number) → {number}

Source:
Since:
Signature:
  • Number -> Number
Category:
  • Math

Returns the value of a number rounded to the nearest integer.

Example
RA.round(0.9); //=> 1
RA.round(5.95); //=> 6
RA.round(5.5); //=> 6
RA.round(5.05); //=> 5
RA.round(-5.05); //=> -5
RA.round(-5.5); //=> -5
RA.round(-5.95); //=> -6
Parameters:
Name Type Description
number number

The number to round
Returns:

The value of the given number rounded to the nearest integer

Type
number

(static) seq(fns, x) → {*}

Source:
Since:
Signature:
  • [(a -> *), (a -> *), ...] -> a -> a
Aliases:
  • sequencing
Category:
  • Function
See also:

Runs the given list of functions in order with the supplied object, then returns the object. Also known as the normal order sequencing combinator.

Acts as a transducer if a transformer is given as second parameter.

Example
RA.seq([console.info, console.log])('foo'); //=> prints 'foo' via info then log

// usage in composition
R.pipe(
  R.concat('prefix '),
  RA.seq([
    console.info, //=> prints 'prefix test'
    console.log //=> prints 'prefix test'
  ]),
  R.toUpper
)('test'); //=> 'PREFIX TEST'
Parameters:
Name Type Description
fns Array

The list of functions to call in order with x whose return values will be thrown away
x *
Returns:

x

Type
*

(static) sign(number) → {number}

Source:
Since:
Signature:
  • Number | String -> Number
Category:
  • Math

Returns the sign of a number, indicating whether the number is positive, negative or zero.

Example
RA.sign(3); //  1
RA.sign(-3); // -1
RA.sign('-3'); // -1
RA.sign(0); //  0
RA.sign(-0); // -0
RA.sign(NaN); // NaN
RA.sign('foo'); // NaN
Parameters:
Name Type Description
number number

A number
Returns:

A number representing the sign of the given argument. If the argument is a positive number, negative number, positive zero or negative zero, the function will return 1, -1, 0 or -0 respectively. Otherwise, NaN is returned

Type
number

(static) skipTake(the, value) → {Array}

Source:
Since:
Signature:
  • Number -> [a] -> [a]
Category:
  • List

When given a number n and an array, returns an array containing every nth element.

Example
RA.skipTake(2, [1,2,3,4]) //=> [1, 3]
RA.skipTake(3, R.range(0, 20)); //=> [0, 3, 6, 9, 12, 15, 18]
Parameters:
Name Type Description
the number

nth element to extract
value Array

the input array
Returns:

An array containing every nth element

Type
Array

(static) sliceFrom(fromIndex, list) → {Array|string}

Source:
Since:
Signature:
  • Number -> [a] -> [a]
Category:
  • List
See also:

Returns the elements of the given list or string (or object with a slice method) from fromIndex (inclusive). Dispatches to the slice method of the second argument, if present.

Example
RA.sliceFrom(1, [1, 2, 3]); //=> [2, 3]
Parameters:
Name Type Description
fromIndex number

The start index (inclusive)
list Array | string

The list or string to slice
Returns:

The sliced list or string

Type
Array | string

(static) sliceTo(toIndex, list) → {Array|string}

Source:
Since:
Signature:
  • Number -> [a] -> [a]
Category:
  • List
See also:

Returns the elements of the given list or string (or object with a slice method) to toIndex (exclusive). Dispatches to the slice method of the second argument, if present.

Example
RA.sliceTo(2, [1, 2, 3]); //=> [1, 2]
Parameters:
Name Type Description
toIndex number

The end index (exclusive)
list Array | string

The list or string to slice
Returns:

The sliced list or string

Type
Array | string

(static) sortByProps(props, list) → {Array.<object>}

Source:
Since:
Signature:
  • [k] -> [{k: v}] -> [{k: v}]
Category:
  • List

Sort a list of objects by a list of props (if first prop value is equivalent, sort by second, etc).

Example
sortByProps(['num'], [{num: 3}, {num: 2}, {num: 1}])
//=> [{num: 1}, {num: 2} {num: 3}]
sortByProps(['letter', 'num'], [{num: 3, letter: 'a'}, {num: 2, letter: 'a'} {num: 1, letter: 'z'}])
//=> [ {num: 2, letter: 'a'}, {num: 3, letter: 'a'}, {num: 1, letter: 'z'}]
sortByProps(['name', 'num'], [{num: 3}, {num: 2}, {num: 1}])
//=> [{num: 1}, {num: 2}, {num: 3}]
Parameters:
Name Type Description
props Array.<string>

A list of properties in the list param to sort by
list Array.<object>

A list of objects to be sorted
Returns:

A new list sorted by the properties in the props param

Type
Array.<object>

(static) spreadPath(pathnon-null, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • [Idx] -> {k: v} -> {k: v}
  • Idx = String | Int
Category:
  • Object
See also:

Spreads object under property path onto provided object. It's like flattenPath, but removes object under the property path.

Example
RA.spreadPath(
  ['b1', 'b2'],
  { a: 1, b1: { b2: { c: 3, d: 4 } } }
); // => { a: 1, c: 3, d: 4, b1: {} };
Parameters:
Name Type Description
path Array.<(string|number)>

The property path to spread
obj Object

The provided object
Returns:

The result of the spread

Type
Object

(static) spreadProp(prop, objnon-null) → (non-null) {Object}

Source:
Since:
Signature:
  • Idx -> {k: v} -> {k: v}
  • Idx = String | Int
Category:
  • Object
See also:

Spreads object under property onto provided object. It's like flattenProp, but removes object under the property.

Example
RA.spreadProp('b', { a: 1, b: { c: 3, d: 4 } }); // => { a: 1, c: 3, d: 4 };
Parameters:
Name Type Description
prop string | number

The property to spread
obj Object

The provided object
Returns:

The result of the spread

Type
Object

(static) stubArray() → {Array}

Source:
Since:
Signature:
  • ... -> Array
Category:
  • Function

A function that returns new empty array on every call.

Example
RA.stubArray(); //=> []
RA.stubArray(1, 2, 3); //=> []
Returns:

New empty array

Type
Array

(static) stubNull() → {null}

Source:
Since:
Signature:
  • ... -> null
Category:
  • Function

A function that returns null.

Example
RA.stubNull(); //=> null
RA.stubNull(1, 2, 3); //=> null
Returns:
Type
null

(static) stubObj() → {Object}

Source:
Since:
Signature:
  • ... -> Object
Aliases:
  • stubObject
Category:
  • Function

This function returns a new empty object.

Example
RA.stubObj(); //=> {}
RA.stubObj(1, 2, 3); //=> {}
Returns:

Returns the new empty object.

Type
Object

(static) stubString() → {string}

Source:
Since:
Signature:
  • ... -> String
Category:
  • Function

A function that returns empty string.

Example
RA.stubString(); //=> ''
RA.stubString(1, 2, 3); //=> ''
Returns:

The empty string

Type
string

(static) stubUndefined() → {undefined}

Source:
Since:
Signature:
  • ... -> undefined
Category:
  • Function

A function that returns undefined.

Example
RA.stubUndefined(); //=> undefined
RA.stubUndefined(1, 2, 3); //=> undefined
Returns:
Type
undefined

(static) subtractNum(subtrahend, minuend) → {number}

Source:
Since:
Signature:
  • Number -> Number -> Number
Category:
  • Math

Subtracts its first argument from its second argument.

Example
RA.subtractNum(3, 5); //=> 2
Parameters:
Name Type Description
subtrahend number

the number to subtract
minuend number

the number to subtract from
Returns:

A number representing the difference of subtracting the subtrahend from the minuend

Type
number

(static) thenCatchP(onFulfilled, onRejected, promise) → {Promise}

Source:
Since:
Signature:
  • (a -> b) -> (c -> d) -> Promise a -> Promise b | d
Category:
  • Function
See also:

Composable shortcut for Promise.then that allows for success and failure callbacks. The thenCatchP function returns a Promise. It takes three arguments: a callback function for the success of the Promise, a callback function for the failure of the Promise, and the promise instance itself.

Example
const promise = Promise.resolve(1);
const add1 = x => x + 1;

RA.thenCatchP(add1, console.error, promise); // => Promise(2)
Parameters:
Name Type Description
onFulfilled function

A Function called if the Promise is fulfilled. This function has one argument, the fulfillment value
onRejected function

A Function called if the Promise is rejected. This function has one argument, the error
promise Promise

Any Promise or Thenable object
Returns:
Type
Promise

(static) thenP(onFulfilled, promise) → {Promise}

Source:
Since:
Deprecated:
  • since v2.12.0; available in ramda@0.26.0 as R.then
Signature:
  • (a -> Promise b | b) -> Promise b
Aliases:
  • then
Category:
  • Function
See also:

Composable shortcut for Promise.then. The thenP function returns a Promise. It takes two arguments: a callback function for the success of the Promise and the promise instance itself.

Example
const promise = Promise.resolve(1);
const add1 = v => v + 1;

RA.thenP(add1, promise); // => Promise(2)
Parameters:
Name Type Description
onFulfilled function

A Function called if the Promise is fulfilled. This function has one argument, the fulfillment value
promise Promise

Any Promise or Thenable object
Returns:

A Promise in the pending status

Type
Promise

(static) toArray(val) → {Array}

Source:
Since:
Signature:
  • * -> [a]
Category:
  • List

Converts value to an array.

Example
RA.toArray([1, 2]); //=> [1, 2]
RA.toArray({'foo': 1, 'bar': 2}); //=> [1, 2]
RA.toArray('abc'); //=> ['a', 'b', 'c']
RA.toArray(1); //=> []
RA.toArray(null); //=> []
Parameters:
Name Type Description
val *

The value to convert
Returns:
Type
Array

(static) trimCharsEnd(chars, value) → {string}

Source:
Since:
Signature:
  • String -> String
Category:
  • String

Removes specified characters from the end of a string.

Example
RA.trimCharsEnd('_-', '-_-abc-_-'); //=> '-_-abc'
Parameters:
Name Type Description
chars string

The characters to trim
value string

The string to trim
Returns:

Returns the trimmed string.

Type
string

(static) trimCharsStart(chars, value) → {string}

Source:
Since:
Signature:
  • String -> String
Category:
  • String

Removes specified characters from the beginning of a string.

Example
RA.trimCharsStart('_-', '-_-abc-_-'); //=> 'abc-_-'
Parameters:
Name Type Description
chars string

The characters to trim
value string

The string to trim
Returns:

Returns the trimmed string.

Type
string

(static) trimEnd(value) → {string}

Source:
Since:
Signature:
  • String -> String
Category:
  • String
See also:

Removes whitespace from the end of a string.

Example
RA.trimEnd('abc   '); //=> 'abc'
Parameters:
Name Type Description
value string

String value to have the whitespace removed from the end
Returns:

A new string representing the calling string stripped of whitespace from its end (right end).

Type
string

(static) trimStart(value) → {string}

Source:
Since:
Signature:
  • String -> String
Category:
  • String

Removes whitespace from the beginning of a string.

Example
RA.trimStart('  abc'); //=> 'abc'
Parameters:
Name Type Description
value string

String value to have the whitespace removed from the beginning
Returns:

A new string representing the calling string stripped of whitespace from its beginning (left end).

Type
string

(static) trunc(number) → {number}

Source:
Since:
Signature:
  • Number | String -> Number
Category:
  • Math

Returns the integer part of a number by removing any fractional digits.

Example
RA.trunc(13.37); //=> 13
RA.trunc(42.84); //=> 42
RA.trunc(0.123); //=>  0
RA.trunc(-0.123); //=> -0
RA.trunc('-1.123'); //=> -1
RA.trunc(NaN); //=> NaN
RA.trunc('foo'); //=> NaN
Parameters:
Name Type Description
number number | string

The number to trunc
Returns:

The integer part of the given number

Type
number

(static) unzipObjWith(fn, obj) → {Array}

Source:
Since:
Signature:
  • (v, k) => [k, v] -> { k: v } -> [[k], [v]]
Category:
  • Object
See also:

Creates a new list out of the supplied object by applying the function to each key/value pairing.

Example
RA.unzipObjWith((v, k) => [`new${k.toUpperCase()}`, 2 * v], { a: 1, b: 2, c: 3 });
//=> [['newA', 'newB', 'newC'], [2, 4, 6]]
Parameters:
Name Type Description
fn function

The function to transform each value-key pair
obj Object

Object to unzip
Returns:

A pair of tw lists: a list of keys and a list of values

Type
Array

(static) viewOr(defaultValue, lens, data) → {*}

Source:
Since:
Signature:
  • a -> Lens s b -> s -> b | a
  • Lens s b = Functor f => (b -> f b) -> s -> f s
Category:
  • Object
See also:

Returns a "view" of the given data structure, determined by the given lens. The lens's focus determines which portion of the data structure is visible. Returns the defaultValue if "view" is null, undefined or NaN; otherwise the "view" is returned.

Example
RA.viewOr('N/A', R.lensProp('x'), {}); // => 'N/A'
RA.viewOr('N/A', R.lensProp('x'), { x: 1 }); // => 1
RA.viewOr('some', R.lensProp('y'), { y: null }); // => 'some'
RA.viewOr('some', R.lensProp('y'), { y: false }); // => false
Parameters:
Name Type Description
defaultValue *

The default value
lens function

Van Laarhoven lens
data *

The data structure
Returns:

"view" or defaultValue

Type
*

(static) weave(fn, config) → {function}

Source:
Since:
Signature:
  • (*... -> *) -> * -> (*... -> *)
Category:
  • Function

Weaves a configuration into function returning the runnable monad like Reader or Free. This allows us to pre-bind the configuration in advance and use the weaved function without need to explicitly pass the configuration on every call.

Example
const { Reader: reader } = require('monet');

const log = value => reader(
  config => config.log(value)
);

// no weaving
log('test').run(console); //=> prints 'test'

// weaving
const wlog = RA.weave(log, console);
wlog('test'); //=> prints 'test'
Parameters:
Name Type Description
fn function

The function to weave
config *

The configuration to weave into fn
Returns:

Auto-curried weaved function

Type
function

(static) weaveLazy(fn, configAccessor) → {function}

Source:
Since:
Signature:
  • (*... -> *) -> (* -> *) -> (*... -> *)
Category:
  • Function

Weaves a configuration into function returning the runnable monad like Reader or Free. This allows us to pre-bind the configuration in advance and use the weaved function without need to explicitly pass the configuration on every call.

Example
const { Reader: reader } = require('monet');

const log = value => reader(
  config => config.log(value)
);

const consoleAccessor = R.always(console);

// no weaving
log('test').run(console); //=> prints 'test'

// weaving
const wlog = RA.weaveLazy(log, consoleAccessor);
wlog('test'); //=> prints 'test'
Parameters:
Name Type Description
fn function

The function to weave
configAccessor function

The function that returns the configuration object
Returns:

Auto-curried weaved function

Type
function

(static) Y(le) → {function}

Source:
Since:
Signature:
  • (a, ... -> b -> b) -> (a, ... -> b)
Category:
  • Function
See also:

Y-combinator

The Y combinator is an interesting function which only works with functional languages, showing how recursion can still be done even without any variable or function declarations, only functions and parameters

Example
const makeFact = givenFact => (n) => {
  if (n < 2) { return 1 }
  return n * givenFact(n - 1);
};

const factorial = RA.Y(makeFact);

factorial(5); //=> 120
Parameters:
Name Type Description
le function

Recursive function maker
Returns:
Type
function

(static) zipObjWith(fn, keys, values) → {Object}

Source:
Since:
Signature:
  • (b, a) -> [k, v] -> [a] -> [b] -> { k: v }
Category:
  • Object
See also:

Creates a new object out of a list of keys and a list of values by applying the function to each equally-positioned pair in the lists. Key/value pairing is truncated to the length of the shorter of the two lists.

Example
RA.zipObjWith((value, key) => [key, `${key}${value + 1}`]), ['a', 'b', 'c'], [1, 2, 3]);
 // => { a: 'a2', b: 'b3', c: 'c4' }
Parameters:
Name Type Description
fn function

The function to transform each value-key pair
keys Array

Array to transform into the properties on the output object
values Array

Array to transform into the values on the output object
Returns:

The object made by pairing up and transforming same-indexed elements of keys and values.

Type
Object