Rambda is a lightweight and fast utility library that provides a variety of functions for functional programming in JavaScript. It is a smaller and faster alternative to Ramda, offering a similar API but with a focus on performance and simplicity.
Currying
Currying is a technique of evaluating functions with multiple arguments, one at a time. Rambda's `curry` function allows you to transform a function so that it can be called with fewer arguments than it expects, returning a new function that takes the remaining arguments.
const R = require('rambda');
const add = R.curry((a, b) => a + b);
const add5 = add(5);
console.log(add5(3)); // 8Composition
Function composition is the process of combining two or more functions to produce a new function. Rambda's `compose` function allows you to create a pipeline of functions that are executed from right to left.
const R = require('rambda');
const add = (a, b) => a + b;
const multiply = (a, b) => a * b;
const addAndMultiply = R.compose(R.multiply(2), R.add(3));
console.log(addAndMultiply(4)); // 14Cloning
Cloning is the process of creating a deep copy of an object. Rambda's `clone` function allows you to create a deep copy of an object, ensuring that changes to the new object do not affect the original object.
const R = require('rambda');
const obj = {a: 1, b: 2};
const clonedObj = R.clone(obj);
console.log(clonedObj); // {a: 1, b: 2}Filtering
Filtering is the process of selecting a subset of items from a collection based on a predicate function. Rambda's `filter` function allows you to filter elements in an array or object based on a provided predicate.
const R = require('rambda');
const isEven = n => n % 2 === 0;
const numbers = [1, 2, 3, 4, 5, 6];
const evenNumbers = R.filter(isEven, numbers);
console.log(evenNumbers); // [2, 4, 6]Mapping
Mapping is the process of transforming each item in a collection using a provided function. Rambda's `map` function allows you to apply a function to each element in an array or object, returning a new array or object with the transformed elements.
const R = require('rambda');
const double = n => n * 2;
const numbers = [1, 2, 3, 4, 5];
const doubledNumbers = R.map(double, numbers);
console.log(doubledNumbers); // [2, 4, 6, 8, 10]Lodash is a popular utility library that provides a wide range of functions for common programming tasks. It is more feature-rich compared to Rambda but also larger in size. Lodash focuses on performance and ease of use, offering a comprehensive set of tools for working with arrays, objects, strings, and more.
Underscore is another utility library that provides a variety of functional programming helpers. It is similar to Lodash but with a smaller footprint and fewer features. Underscore offers a core set of functions for working with collections, arrays, objects, and functions, making it a good choice for projects that need a lightweight utility library.
Ramda is a functional programming library for JavaScript that emphasizes immutability and pure functions. It offers a similar API to Rambda but with a larger set of functions and a focus on functional programming principles. Ramda is more feature-rich but also larger in size compared to Rambda.
Faster alternative to Ramda in just 12kB - Documentation
I admire Ramda, as it is great library in what it does. My main problem was its size. Even custom builds didn't deliver satisfactory results. Also I already had Ramda habits and I didn't want to switch to Lodash.
Then I realized that my best solution was to publish a library that recreates the functionality of some Ramda methods with less code.
Rambda partially shadows Ramda's API, so you need to check in Rambda's documentation, if the methods you need are available.
Generally speaking, if you have never used methods such as R.transduce, Rambda API should be enough for your needs.
const R = require('rambda')
const result = R.compose(
R.filter( R.equals( 2 ) ),
R.map( R.add( 1 ) )
)({ a: 1, b: 2, c: 3 })
console.log(result) // => '{a: 2}'
Use yarn add rambda for Webpack and Node.js usage
For browser usage include in your HTML
https://cdnjs.cloudflare.com/ajax/libs/rambda/0.9.1/webVersion.js
Rambda's type detect async functions and unresolved Promises. The returned values are 'Async' and 'Promise'.
Rambda's equals doesn't protect against circular structures as Ramda.equals does.
Rambda's path, pick and omit accepts both string and array as condition argument('x.y.z' == ['x','y','z']).
Rambda's partialCurry, typedDefaultTo, typedPathOr, includes, padStart and padEnd are not part of Ramda API.
Rambda's reverse modifies the array, instead of returning reversed copy of it.
If you need more Ramda methods in Rambda, you may either submit a
PRor check the extended version of Rambda - Rambdax
add(a: Number, b: Number): Number
R.add(2, 3) // => 5
addIndex(fn: Function): Function
const mapWithIndex = R.addIndex(R.map)
mapWithIndex(
(val, index) => `${val} - ${index}`,
["A", "B", "C"]
) // => ["A - 0", "B - 1", "C - 2"]
adjust(replaceFn: Function, i:Number, arr:Array): Array
It replaces i index in arr with the result of replaceFn(arr[i]).
R.adjust(a => a + 1, 0, [0, 100]) // => [1, 100]
all(fn: Function, arr: Array): Boolean
It returns true if all members of array arr returns true, when applied as argument to function fn.
const arr = [ 0, 1, 2, 3, 4 ]
const fn = x => x > -1
R.all(fn, arr) // => true
allPass(rules: Array, input: any): Boolean
It returns true if all functions of rules return true, when input is their argument.
const input = {
a : 1,
b : 2,
}
const rules = [
x => x.a === 1,
x => x.b === 2,
]
R.allPass(conditionArr, obj) // => true
always(x: any): Function
It returns function that always returns x.
const fn = R.always(7)
fn()// => 7
fn()// => 7
any(condition: Function, arr: Array): Boolean
It returns true if at least one member of arr returns true,
when passed to the condition function.
R.any(a => a * a > 8)([1, 2, 3]) // => true
R.any(a => a * a > 10)([1, 2, 3]) // => false
append(valueToAppend: any, arr: Array): Array
R.append('foo', ['bar', 'baz']) // => ['foo', 'bar', 'baz']
both(x: Function, y: Function, input: any): Boolean
It returns true if both function x and function y return true, when input is their argument.
const fn = R.both(
a => a > 10,
a => a < 20
)
fn(15) //=> true
fn(30) //=> false
compose(fn1: Function, ... , fnN: Function): any
It performs right-to-left function composition.
const result = R.compose(
R.map(x => x * 2)
R.filter(x => x > 2),
)([1, 2, 3, 4])
console.log(result) // => [6, 8]
complement(fn: Function): Function
It returns complemented function that accept input as argument.
The return value of complemented is the negative boolean value of fn(input).
R.complement(R.always(0)) // => true
R.complement(R.always(true)) // => false
concat(x: Array|String, y: Array|String): Array|String
It returns new string or array, which is result merging x and y.
R.concat([1, 2])([3, 4]) // => [1, 2, 3, 4]
R.concat('foo', 'bar') // => 'foobar'
contains(valueToFind: any, arr: Array): Boolean
It returns true if valueToFind is part of arr.
R.contains(2, [1, 2]) // => true
R.contains(3, [1, 2]) // => false
curry(fn: Function): Function
It returns curried version of fn.
const addFourNumbers = (a, b, c, d) => a + b + c + d
const curriedAddFourNumbers = R.curry(addFourNumbers)
const f = curriedAddFourNumbers(1, 2)
const g = f(3)
g(4) // => 10
defaultTo(defaultValue: T, inputArgument: any): T
It returns defaultValue, if inputArgument is undefined, null or NaN.
It returns inputArgument in any other case.
R.defaultTo('foo', undefined) // => 'foo'
R.defaultTo('foo', 'bar') // => 'bar'
R.defaultTo('foo', 1) // => 1
R.divide(71, 100) // => 0.71
drop(howManyToDrop: Number, arrOrStr: Array|String): Array|String
It returns arrOrStr with howManyToDrop items dropped from the left.
R.drop(1, ['foo', 'bar', 'baz']) // => ['bar', 'baz']
R.drop(1, 'foo') // => 'oo'
dropLast(howManyToDrop: Number, arrOrStr: Array|String): Array|String
It returns arrOrStr with howManyToDrop items dropped from the right.
R.dropLast(1, ['foo', 'bar', 'baz']) // => ['foo', 'bar']
R.dropLast(1, 'foo') // => 'fo'
endsWith(x: any, arrOrStr: Array|String): Boolean
R.endsWith(
'bar',
"foo-bar"
) // => true
R.endsWith(
'baz',
"foo-bar"
) // => false
const fn = R.either(
a => a > 10,
a => a % 2 === 0
)
fn(15) //=> true
fn(6) //=> true
fn(7) //=> false
equals(a: any, b: any): Boolean
It returns equality match between a and b.
It doesn't handle cyclical data structures.
R.equals(1, 1) // => true
R.equals({}, {}) // => false
R.equals([1, 2, 3], [1, 2, 3]) // => true
R.F() // => false
filter(filterFn: Function, arr: Array): Array
Filters arr throw boolean returning filterFn
const filterFn = a => a % 2 === 0
R.filter(filterFn, [1, 2, 3, 4]) // => [2, 4]
find(findFn: Function, arr: Array): T|undefined
It returns undefined or the first element of arr satisfying findFn.
const findFn = a => R.type(a.foo) === "Number"
const arr = [{foo: "bar"}, {foo: 1}]
R.find(findFn, arr) // => {foo: 1}
findIndex(findFn: Function, arr: Array): Number
It returns -1 or the index of the first element of arr satisfying findFn.
const findFn = a => R.type(a.foo) === "Number"
const arr = [{foo: "bar"}, {foo: 1}]
R.find(findFn, arr) // => 1
flatten(arr: Array): Array
R.flatten([ 1, [ 2, [ 3 ] ] ])
// => [ 1, 2, 3 ]
flip(fn: Function): Function
It returns function which calls fn with exchanged first and second argument.
const subtractFlip = R.flip(R.subtract)
R.subtractFlip(1,7)
// => 6
Note that it works only for functions that expects two arguments. If third argument is passed, then undefined is returned.
has(prop: String, obj: Object): Boolean
true if obj has property prop.R.has("a", {a: 1}) // => true
R.has("b", {a: 1}) // => false
head(arrOrStr: Array|String): any
It returns the first element of arrOrStr.
R.head([1, 2, 3]) // => 1
R.head('foo') // => 'f'
identity(x: T): T
It just passes back the supplied arguments.
R.identity(7) // => 7
ifElse(condition: Function, ifFn: Function, elseFn: Function): Function
It returns function, which expect input as argument and returns finalResult.
When the function is called, a value answer is generated as a result of condition(input).
If answer is true, then finalResult is equal to ifFn(input).
If answer is false, then finalResult is equal to elseFn(input).
const fn = R.ifElse(
x => x > 10,
x => x*2,
x => x*10
)
fn(8) // => 80
fn(11) // => 22
indexOf(valueToFind: any, arr: Array): Number
It returns -1 or the index of the first element of arr equal of valueToFind.
R.indexOf(1, [1, 2]) // => 0
init(arrOrStr: Array|String): Array|String
arrOrStr.R.init([1, 2, 3]) // => [1, 2]
R.init('foo') // => 'fo'
join(separator: String, arr: Array): String
R.join('-', [1, 2, 3]) // => '1-2-3'
isNil(x: any): Boolean
It returns true is x is either null or undefined.
R.isNil(null) // => true
R.isNil(1) // => false
last(arrOrStr: Array|String): any
arrOrStr.R.last(['foo', 'bar', 'baz']) // => 'baz'
R.last('foo') // => 'o'
lastIndexOf(x: any, arr: Array): Number
R.lastIndexOf(1, [1, 2, 3, 1, 2]) // => 3
R.lastIndexOf(10, [1, 2, 3, 1, 2]) // => -1
length(arrOrStr: Array|String): Number
R.length([1, 2, 3]) // => 3
map(mapFn: Function, arr: Array): Array
It returns the result of looping through arr with mapFn.
const mapFn = x => x * 2;
R.map(mapFn, [1, 2, 3]) // => [2, 4, 6]
match(regExpression: Regex, str: String): Array
R.match(/([a-z]a)/g, 'bananas') // => ['ba', 'na', 'na']
merge(a: Object, b: Object)
It returns result of Object.assign({}, a, b).
R.merge({ 'foo': 0, 'bar': 1 }, { 'foo': 7 })
// => { 'foo': 7, 'bar': 1 }
modulo(a: Number, b: Number): Number
It returns the remainder of operation a/b.
R.module(14,3) // => 2
multiply(a: Number, b: Number): Number
It returns the result of operation a*b.
R.module(14,3) // => 2
not(x: any): Boolean
It returns inverted boolean version of input x.
R.not(true); //=> false
R.not(false); //=> true
R.not(0); //=> true
R.not(1); //=> false
omit(propsToOmit: Array, obj: Object): Object
It returns a partial copy of an obj with omitting propsToOmit
R.omit(['a', 'd'], {a: 1, b: 2, c: 3}) // => {b: 2, c: 3}
path(pathToSearch: Array|String, obj: Object): any
If pathToSearch is 'a.b' then it will return 1 if obj is {a:{b:1}}.
It will return undefined, if such path is not found.
R.path('a.b', {a: {b: 1}}) // => 1
R.path(['a', 'b'], {a: {b: 2}}) // => 2
R.path(['a', 'c'], {a: {b: 2}}) // => undefined
pathOr(defaultValue: any, pathToSearch: Array|String, obj: Object): any
pathFound is the result of calling R.path(pathToSearch, obj).
If pathFound is undefined, null or NaN, then defaultValue will be returned.
pathFound is returned in any other case.
R.pathOr(1, 'a.b', {a: {b: 2}}) // => 2
R.pathOr(1, ['a', 'b'], {a: {b: 2}}) // => 2
R.pathOr(1, ['a', 'c'], {a: {b: 2}}) // => 1
partialCurry(fn: Function|Async, a: Object, b: Object): Function|Promise
When called with function fn and first set of input a, it will return a function.
This function will wait to be called with second set of input b and it will invoke fn with the merged object of a over b.
fn can be asynchronous function. In that case a Promise holding the result of fn is returned.
See the example below:
const fn = ({a, b, c}) => {
return (a * b) + c
}
const curried = R.partialCurry(fn, {a: 2})
curried({b: 3, c: 10}) // => 16
Note that partialCurry is method specific for Rambda and the method is not part of Ramda's API
You can read my argumentation for creating partialCurry here
pick(propsToPick: Array, obj: Object): Object
It returns a partial copy of an obj containing only propsToPick properties.
R.pick(['a', 'c'], {a: 1, b: 2}) // => {a: 1}
pipe(fn1: Function, ... , fnN: Function): any
It performs left-to-right function composition.
const result = R.pipe(
R.filter(val => val > 2),
R.map(a => a * 2)
)([1, 2, 3, 4])
console.log(result) // => [6, 8]
pluck(property: String, arr: Array): Array
It returns list of the values of property taken from the objects in array of objects arr.
R.pluck('a')([{a: 1}, {a: 2}, {b: 3}]) // => [1, 2]
prepend(x: any, arr: Array): Array
It adds x to the start of the array arr.
R.prepend('foo', ['bar', 'baz']) // => ['foo', 'bar', 'baz']
prop(propToFind: String, obj: Object): any
It returns undefined or the value of property propToFind in obj
R.prop('x', {x: 100}) // => 100
R.prop('x', {a: 1}) // => undefined
propEq(propToFind: String, valueToMatch: any, obj: Object): Boolean
It returns true if obj has property propToFind and its value is equal to valueToMatch
const propToFind = "foo"
const valueToMatch = 0
R.propEq(propToFind, valueToMatch)({foo: 0}) // => true
R.propEq(propToFind, valueToMatch)({foo: 1}) // => false
range(start: Number, end: Number): Array
It returns a array of numbers from start(inclusive) to end(exclusive).
R.range(0, 2) // => [0, 1]
reduce(iteratorFn: Function, accumulator: any, array: Array): any
It returns a single item by iterating through the list, successively calling the iterator function iteratorFn and passing it an accumulator value and the current value from the array, and then passing the result to the next call.
The iterator function behaves like the native callback of the Array.prototype.reduce method.
const iteratorFn = (acc, val) => acc + val
R.reduce(iteratorFn, 1, [1, 2, 3]) // => 7
repeat(valueToRepeat: T, num: Number): Array
R.repeat('foo', 2) // => ['foo', 'foo']
replace(strOrRegex: String|Regex, replacer: String, str: String): String
Replace strOrRegex found in str with replacer
R.replace('foo', 'bar', 'foo foo') // => 'bar foo'
R.replace(/foo/, 'bar', 'foo foo') // => 'bar foo'
R.replace(/foo/g, 'bar', 'foo foo') // => 'bar bar'
!!! It modifies the array instead of returning new copy, as original Ramda method does.
const arr = [1, 2]
R.reverse(arr)
console.log(arr) // => [2, 1]
sort(sortFn: Function, arr: Array): Array
It returns copy of arr sorted by sortFn.
sortFn must return Number
const sortFn = (a, b) => a - b
R.sort(sortFn, [3, 1, 2]) // => [1, 2, 3]
sortBy(sortFn: Function, arr: Array): Array
It returns copy of arr sorted by sortFn.
sortFn must return value for comparison
const sortFn = obj => obj.foo
R.sortBy(sortFn, [
{foo: 1},
{foo: 0}
])
// => [{foo: 0}, {foo: 1}]
split(separator: String, str: String): Array
R.split('-', 'a-b-c') // => ['a', 'b', 'c']
splitEvery(sliceLength: Number, arrOrString: Array|String): Array
arrOrStr into slices of sliceLengthR.splitEvery(2, [1, 2, 3]) // => [[1, 2], [3]]
R.splitEvery(3, 'foobar') // => ['foo', 'bar']
startsWith(x: any, arrOrStr: Array|String): Boolean
R.endsWith(
'bar',
"foo-bar"
) // => true
R.endsWith(
'baz',
"foo-bar"
) // => false
subtract(a: Number, b: Number): Number
R.subtract(3, 1) // => 2
R.T() // => true
tail(arrOrStr: Array|String): Array|String
arrOrStrR.tail([1, 2, 3]) // => [2, 3]
R.tail('foo') // => 'oo'
take(num: Number, arrOrStr: Array|String): Array|String
num elements of arrOrStr.R.take(1, ['foo', 'bar']) // => ['foo']
R.take(2, ['foo']) // => 'fo'
takeLast(num: Number, arrOrStr: Array|String): Array|String
num elements of arrOrStr.R.takeLast(1, ['foo', 'bar']) // => ['bar']
R.takeLast(2, ['foo']) // => 'oo'
test(regExpression: Regex, str: String): Boolean
str matches regExpressionR.test(/^f/, 'foo') // => true
R.test(/^f/, 'bar') // => false
toLower(str: String): String
R.toLower('FOO') // => 'foo'
toString(x: any): String
R.toString([1, 2]) // => '1,2'
toUpper(str: String): String
R.toUpper('foo') // => 'FOO'
trim(str: String): String
R.trim(' foo ') // => 'foo'
type(a: any): String
R.type(() => {}) // => "Function"
R.type(async () => {}) // => "Async"
R.type([]) // => "Array"
R.type({}) // => "Object"
R.type('foo') // => "String"
R.type(1) // => "Number"
R.type(true) // => "Boolean"
R.type(null) // => "Null"
R.type(/[A-z]/) // => "RegExp"
const delay = ms => new Promise(resolve => {
setTimeout(function () {
resolve()
}, ms)
})
R.type(delay) // => "Promise"
typedDefaultTo(defaultValue: T, inputArgument: any): T
It returns defaultValue, if inputArgument and defaultValue has different types.
It returns inputArgument in any other case.
R.typedDefaultTo('foo', undefined) // => 'foo'
R.typedDefaultTo('foo', 'bar') // => 'bar'
R.typedDefaultTo('foo', 1) // => 'foo'
typedDefaultTo is method specific for Rambda and the method is not part of Ramda's APItypedPathOr(defaultValue: any, pathToSearch: Array|String, obj: Object): any
pathFound is the result of calling R.path(pathToSearch, obj).
If pathFound has different type than defaultValue, then defaultValue will be returned.
If pathFound has the same type as defaultValue, then pathFound will be returned.
R.typedPathOr(1, 'a.b', {a: {b: 2}}) // => 2
R.typedPathOr(1, 'a.b', {a: {b: 'foo'}}) // => 1
typedPathOr is method specific for Rambda and the method is not part of Ramda's APIuniq(arr: Array): Array
It returns a new array containing only one copy of each element in arr.
R.uniq([1, 1, 2, 1]) // => [1, 2]
R.uniq([1, '1']) // => [1, '1']
update(i: Number, replaceValue: any, arr: Array): Array
It returns a new copy of the arr with the element at i index
replaced with replaceValue.
R.update(0, "foo", ['bar', 'baz']) // => ['foo', baz]
values(obj: Object): Array
It returns array with of all values in obj.
R.values({a: 1, b: 2}) // => [1, 2]
includes(x: any, arrOrStr: Array|String): Boolean
R.includes(1, [1, 2]) // => true
R.includes('oo', 'foo') // => true
R.includes('z', 'foo') // => false
Note that this method is not part of Ramda API.
padEnd(x: Number, str: String): String
R.padEnd(3, 'foo') // => 'foo '
Note that this method is not part of Ramda API.
padStart(x: Number, str: String): String
R.padStart(3, 'foo') // => ' foo'
Note that this method is not part of Ramda API.
I haven't tested it fully, but the partial test shows that Ramda definitions can be used.
You need to replace declare module ramda with declare module rambda on line 10 and store the file as rambda.js in your flow-typed folder
defaultTo to a new method typedDefaultTo; make defaultTo follow Ramda spec; add pathOr; add typedPathOr.R.pipe PR#35R.isNilWebpack with Rollup - PR29R.tap and R.identityR.all, R.allPass, R.both, R.either and R.complementnpm test before npm publish the hard wayR.always, R.T and R.Fconcat, padStart, padEnd, lastIndexOf, toString, reverse, endsWith and startsWith methodsR.ifElseR.not, R.includes | Take string as condition for R.pick and R.omitR.valuesR.omitR.curry, which used to return incorrectly function when called with more argumentses2015; Approve PR #10 - add R.addIndex to the APIPromise support for R.typeR.reduce to the APIcurry to partialCurry; add new method curry, which works just like Ramda's currydocsifyIf you want to add another Ramda method to the API, please feel free to submit a PR .
The only requirement is the new method to have exact or very close implementation compared to the corresponding Ramda method.
I give you example steps of the PR process.
Create a method file in
modulesfolder.
If the new method is R.endsWith, then the created file will be ./modules/endsWith.js
Write the function declaration and function's logic.
function endsWith(x, arrOrStr){
return arrOrStr.endsWith(x)
}
Any method, which takes more than one argument, should be curried.
We can use the standard curring used throughout Rambda.
function endsWith(x, arrOrStr){
if(arrOrStr === undefined){
return arrOrStrHolder => endsWith(x, arrOrStrHolder)
}
return arrOrStr.endsWith(x)
}
module.exports = endsWith
Or we can also use R.curry, but it is not as performant as the example above.
const curry = require('./curry')
function endsWith(x, arrOrStr){
if(arrOrStr === undefined){
return holder => endsWith(x, arrOrStr)
}
return arrOrStr.endsWith(x)
}
module.exports = curry(endsWith)
Edit
rambda.jsfile
Exported methods are sorted alphabetically
exports.dropLast = require("./modules/dropLast")
exports.endsWith = require("./modules/endsWith")
exports.equals = require("./modules/equals")
Write your test cases
Create file endsWith.js in folder __tests__
const R = require('../rambda')
test('endsWith', () => {
expect(R.endsWith('oo')('foo')).toBeTruthy()
})
Run
npm testto validate your tests
Edit
./README.mdto add documentation
Note that your documentation should match the pattern visible across ./README.md
Lint your files
npm run lint modules/endsWith.js
npm run lint __tests__/endsWith.js
Submit PR
Expect response within 2 days.
Projects using Rambda
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FAQs
Lightweight and faster alternative to Ramda with included TS definitions
The npm package rambda receives a total of 551,776 weekly downloads. As such, rambda popularity was classified as popular.
We found that rambda demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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