Rambdax

Extended version of Rambda(utility library) - Documentation

Rambda is smaller and faster alternative to the popular functional programming library Ramda. - Documentation

❯ Differences between Rambda and Rambdax

Rambdax passthrough all Rambda methods and introduce some new functions.

The idea of Rambdax is to extend Rambda without worring for Ramda compatibility.

❯ Example use

import { composeAsync, filter, delay, mapAsync } from 'rambdax'

const result = await composeAsync(
  mapAsync(async x => {
    await delay(100)
    return x + 1
  }),
  filter(x => x > 1)
)([1, 2, 3])
// => [3, 4]

You can test this example in Rambda's REPL

• Differences between Rambda and Ramda
• API
• Changelog

❯ Rambdax's advantages

TypeScript included

TypeScript definitions are included in the library, in comparison to Ramda, where you need to additionally install @types/ramda.

Still, you need to be aware that functional programming features in TypeScript are in development, which means that using R.compose/R.pipe can be problematic.

Important - Rambdax version 9.0.0(or higher) requires TypeScript version 4.3.3(or higher).

Dot notation for R.path, R.paths, R.assocPath and R.lensPath

Standard usage of R.path is R.path(['a', 'b'], {a: {b: 1} }).

In Rambda you have the choice to use dot notation(which is arguably more readable):

R.path('a.b', {a: {b: 1} })

Comma notation for R.pick and R.omit

Similar to dot notation, but the separator is comma(,) instead of dot(.).

R.pick('a,b', {a: 1 , b: 2, c: 3} })
// No space allowed between properties

Extendable with Ramda community projects

Rambdax implements some methods from Ramda community projects, such as R.lensSatisfies, R.lensEq and R.viewOr.

Understandable source code due to little usage of internals

Ramda uses a lot of internals, which hides a lot of logic. Reading the full source code of a method can be challenging.

Better VSCode experience

If the project is written in Javascript, then go to source definition action will lead you to actual implementation of the method.

Deno support

import * as R from "https://deno.land/x/rambdax/mod.ts";

Alternative TS definitions

Alternative TS definitions are available as rambdax/immutable. These are Rambdax definitions linted with ESLint functional/prefer-readonly-type plugin.

❯ Missing Ramda methods

❯ Install

• yarn add rambdax

• For UMD usage either use ./dist/rambdax.umd.js or the following CDN link:

https://unpkg.com/rambdax@CURRENT_VERSION/dist/rambdax.umd.js

• with deno

import {add} from "https://deno.land/x/rambda/mod.ts";

Differences between Rambda and Ramda

• Rambda's type detects async functions and unresolved Promises. The returned values are 'Async' and 'Promise'.

• Rambda's type handles NaN input, in which case it returns NaN.

• Rambda's forEach can iterate over objects not only arrays.

• Rambda's map, filter, partition when they iterate over objects, they pass property and input object as predicate's argument.

• Rambda's filter returns empty array with bad input(null or undefined), while Ramda throws.

• Ramda's clamp work with strings, while Rambda's method work only with numbers.

• Ramda's indexOf/lastIndexOf work with strings and lists, while Rambda's method work only with lists as iterable input.

• Error handling, when wrong inputs are provided, may not be the same. This difference will be better documented once all brute force tests are completed.

• TypeScript definitions between rambda and @types/ramda may vary.

❯ Benchmarks

❯ Used by

• ESLint plugin Mocha

• WatermelonDB

• Walmart Canada reported by w-b-dev

• VSCode Slack integration

• Webpack PostCSS

• MobX-State-Tree decorators

• Rewrite of the Betaflight configurator

• MineFlayer plugin

API

add

It adds a and b.

:boom: It doesn't work with strings, as the inputs are parsed to numbers before calculation.

Try this R.add example in Rambda REPL

addIndex

Try this R.addIndex example in Rambda REPL

addIndexRight

Same as R.addIndex, but it will passed indexes are decreasing, instead of increasing.

adjust

adjust<T>(index: number, replaceFn: (x: T) => T, list: T[]): T[]

It replaces index in array list with the result of replaceFn(list[i]).

const result = R.adjust(
  0,
  a => a + 1,
  [0, 100]
) // => [1, 100]

Try this R.adjust example in Rambda REPL

all

all<T>(predicate: (x: T) => boolean, list: T[]): boolean

It returns true, if all members of array list returns true, when applied as argument to predicate function.

const list = [ 0, 1, 2, 3, 4 ]
const predicate = x => x > -1

const result = R.all(predicate, list)
// => true

Try this R.all example in Rambda REPL

allFalse

allFalse(...inputs: any[]): boolean

It returns true if all inputs arguments are falsy(empty objects and empty arrays are considered falsy).

Functions are valid inputs, but these functions cannot have their own arguments.

This method is very similar to R.anyFalse, R.anyTrue and R.allTrue

R.allFalse(0, null, [], {}, '', () => false)
// => true

Try this R.allFalse example in Rambda REPL

allPass

allPass<T>(predicates: ((x: T) => boolean)[]): (input: T) => boolean

It returns true, if all functions of predicates return true, when input is their argument.

const input = {
  a : 1,
  b : 2,
}
const predicates = [
  x => x.a === 1,
  x => x.b === 2,
]
const result = R.allPass(predicates)(input) // => true

Try this R.allPass example in Rambda REPL

allTrue

allTrue(...input: any[]): boolean

It returns true if all inputs arguments are truthy(empty objects and empty arrays are considered falsy).

R.allTrue(1, true, {a: 1}, [1], 'foo', () => true)
// => true

Try this R.allTrue example in Rambda REPL

allType

allType(targetType: RambdaTypes): (...input: any[]) => boolean

It returns a function which will return true if all of its inputs arguments belong to targetType.

:boom: targetType is one of the possible returns of R.type

const targetType = 'String'

const result = R.allType(
  targetType
)('foo', 'bar', 'baz')
// => true

Try this R.allType example in Rambda REPL

always

It returns function that always returns x.

Try this R.always example in Rambda REPL

and

Logical AND

Try this R.and example in Rambda REPL

any

any<T>(predicate: (x: T) => boolean, list: T[]): boolean

It returns true, if at least one member of list returns true, when passed to a predicate function.

const list = [1, 2, 3]
const predicate = x => x * x > 8
R.any(fn, list)
// => true

Try this R.any example in Rambda REPL

anyFalse

anyFalse(...input: any[]): boolean

It returns true if any of inputs is falsy(empty objects and empty arrays are considered falsy).

R.anyFalse(1, {a: 1}, [1], () => false)
// => true

Try this R.anyFalse example in Rambda REPL

anyPass

anyPass<T>(predicates: ((x: T) => boolean)[]): (input: T) => boolean

It accepts list of predicates and returns a function. This function with its input will return true, if any of predicates returns true for this input.

const isBig = x => x > 20
const isOdd = x => x % 2 === 1
const input = 11

const fn = R.anyPass(
  [isBig, isOdd]
)

const result = fn(input) 
// => true

Try this R.anyPass example in Rambda REPL

anyTrue

anyTrue(...input: any[]): boolean

It returns true if any of inputs arguments are truthy(empty objects and empty arrays are considered falsy).

R.anyTrue(0, null, [], {}, '', () => true)
// => true

Try this R.anyTrue example in Rambda REPL

anyType

anyType(targetType: RambdaTypes): (...input: any[]) => boolean

It returns a function which will return true if at least one of its inputs arguments belongs to targetType.

targetType is one of the possible returns of R.type

:boom: targetType is one of the possible returns of R.type

const targetType = 'String'

const result = R.anyType(
  targetType
)(1, {}, 'foo')
// => true

Try this R.anyType example in Rambda REPL

ap

ap<T, U>(fns: Array<(a: T) => U>[], vs: T[]): U[]

It takes a list of functions and a list of values. Then it returns a list of values obtained by applying each function to each value.

const result = R.ap(
  [
    x => x + 1,
    x => x + 2,
  ],
  [1, 2, 3]
)
// => [2, 3, 4, 3, 4, 5]

Try this R.ap example in Rambda REPL

aperture

aperture<N extends number, T>(n: N, list: T[]): Array<Tuple<T, N>> | []

It returns a new list, composed of consecutive n-tuples from a list.

const result = R.aperture(2, [1, 2, 3, 4])
// => [[1, 2], [2, 3], [3, 4]]

Try this R.aperture example in Rambda REPL

append

append<T>(xToAppend: T, iterable: T[]): T[]

It adds element x at the end of iterable.

const x = 'foo'

const result = R.append(x, ['bar', 'baz'])
// => ['bar', 'baz', 'foo']

Try this R.append example in Rambda REPL

apply

apply<T = any>(fn: (...args: any[]) => T, args: any[]): T

It applies function fn to the list of arguments.

This is useful for creating a fixed-arity function from a variadic function. fn should be a bound function if context is significant.

const result = R.apply(Math.max, [42, -Infinity, 1337])
// => 1337

Try this R.apply example in Rambda REPL

applyDiff

applyDiff<Output>(rules: ApplyDiffRule[], obj: object): Output

It changes paths in an object according to a list of operations. Valid operations are add, update and delete. Its use-case is while writing tests and you need to change the test data.

Note, that you cannot use update operation, if the object path is missing in the input object. Also, you cannot use add operation, if the object path has a value.

const obj = {a: {b:1, c:2}}
const rules = [
  {op: 'remove', path: 'a.c'},
  {op: 'add', path: 'a.d', value: 4},
  {op: 'update', path: 'a.b', value: 2},
]
const result = R.applyDiff(rules, Record<string, unknown>)
const expected = {a: {b: 2, d: 4}}

// => `result` is equal to `expected`

Try this R.applyDiff example in Rambda REPL

applySpec

applySpec<Spec extends Record<string, AnyFunction>>(
  spec: Spec
): (
  ...args: Parameters<ValueOfRecord<Spec>>
) => { [Key in keyof Spec]: ReturnType<Spec[Key]> }

:boom: The currying in this function works best with functions with 4 arguments or less. (arity of 4)

const fn = R.applySpec({
  sum: R.add,
  nested: { mul: R.multiply }
})
const result = fn(2, 4) 
// => { sum: 6, nested: { mul: 8 } }

Try this R.applySpec example in Rambda REPL

applyTo

Try this R.applyTo example in Rambda REPL

ascend

Try this R.ascend example in Rambda REPL

assoc

It makes a shallow clone of obj with setting or overriding the property prop with newValue.

:boom: This copies and flattens prototype properties onto the new object as well. All non-primitive properties are copied by reference.

Try this R.assoc example in Rambda REPL

assocPath

assocPath<Output>(path: Path, newValue: any, obj: object): Output

It makes a shallow clone of obj with setting or overriding with newValue the property found with path.

const path = 'b.c'
const newValue = 2
const obj = { a: 1 }

const result = R.assocPath(path, newValue, obj)
// => { a : 1, b : { c : 2 }}

Try this R.assocPath example in Rambda REPL

binary

Try this R.binary example in Rambda REPL

bind

bind<F extends AnyFunction, T>(fn: F, thisObj: T): (...args: Parameters<F>) => ReturnType<F>

Creates a function that is bound to a context.

:boom: R.bind does not provide the additional argument-binding capabilities of Function.prototype.bind.

const log = R.bind(console.log, console)
const result = R.pipe(
  R.assoc('a', 2), 
  R.tap(log), 
  R.assoc('a', 3)
)({a: 1}); 
// => result - `{a: 3}`
// => console log - `{a: 2}`

Try this R.bind example in Rambda REPL

both

both(pred1: Pred, pred2: Pred): Pred

It returns a function with input argument.

This function will return true, if both firstCondition and secondCondition return true when input is passed as their argument.

const firstCondition = x => x > 10
const secondCondition = x => x < 20
const fn = R.both(firstCondition, secondCondition)

const result = [fn(15), fn(30)]
// => [true, false]

Try this R.both example in Rambda REPL