Functional Programming was always a weird "why would you use this" way of coding as I've primarily been OOP. I set out to change my view on that and learn more about it and when to use it. These are some of the functions I collected/made along the way. They are all ES6/ESM, the parameter order for most lends itself to currying + composing. Still a little iffy on the Hindley-milner signatures so they may be slightly off.
- associate()
Sets the given property and value on the object. Returning a new object.
- average()
Averages the given array values
- A()
Calls the given function with the given value.
- Fork()
Takes a joiner func, and two other funcs and a value. The value is given to both funcs and the results of each of these is given to the joiner func.
- I()
Returns the given value.
- K()
Takes two values and returns the given first.
- OR()
Given two functions that take the same value, returns the first if the result is truthy, otherwise, the second.
- T()
Calls the given function with the given value. (Reverse order of apply)
- compact()
Removes falsey values from an array.
- compose()
Performs right-to-left function composition.
- concat()
Concatenates two String|Arrays together. Returns empty array if value arent of the same type or not String|Array.
- concatN()
Concatenates N Arrays together.
- curry()
Wraps the given function, if the number of provided args is sufficient, call the passed function fn. Otherwise, return a wrapped function fn that expects the rest of the arguments. If you want to curry a function that accepts a variable number of arguments (a variadic function), you can optionally pass the number of arguments to the second parameter arity.
- difference()
Returns the difference between two arrays.
- distinct()
Returns all of the distinct values of an array.
- distinctN()
Returns all of the distinct values of the given arrays.
- each()
Applies the given func to each element in the array.
- every()
Determines if all element in an array satisfy the given test function
- filter()
Filters the array using the given function.
- find()
Finds the first element that satisfies the given test func.
- flatten()
Flattens single nested array.
- isArray()
Determines if the given value is an array.
- isFunction()
Determines if the given value is a function.
- isNumber()
Determines if the given value is a number.
- isObject()
Determines if the given value is an object.
- isString()
Determines if the given value is a string.
- not()
Negates the given boolean-like value.
- tap()
Calls the given function with the given value and returns the value.
Sets the given property and value on the object. Returning a new object.
Kind: global function
Signature: associate :: String k -> {} -> v -> {k: v}
Example
const obj = associate('c', { a: b }, d) // { a: b, c: d }Averages the given array values
Kind: global function
Signature: average :: [Number] -> Number
Example
average([ 1, 2, 3 ]); // 2
average(1, 2, 3); // 2
average(); // 0Calls the given function with the given value.
Kind: global function
Signature: A :: (a -> b) -> a -> b
Aka: apply
Takes a joiner func, and two other funcs and a value. The value is given to both funcs and the results of each of these is given to the joiner func.
Kind: global function
Signature: Fork :: (b -> c -> d) -> (a -> b) -> (a -> c) -> a -> d
Aka: join
Returns the given value.
Kind: global function
Signature: I :: a -> a
Aka: identity
Takes two values and returns the given first.
Kind: global function
Signature: K :: a -> b -> a
Aka: constant
Given two functions that take the same value, returns the first if the result is truthy, otherwise, the second.
Kind: global function
Signature: OR :: (a -> b) -> (a -> b) -> b
Aka: alternation
Calls the given function with the given value. (Reverse order of apply)
Kind: global function
Signature: T :: a -> (a -> b) -> b
Aka: thrush, applyTo
Removes falsey values from an array.
Kind: global function
Signature: compact :: [a] -> [a]
Example
compact([ 0, 1, false, 2, '', 3, 'a', 'e' * 23, NaN, 's', 34 ]); // [ 1, 2, 3, 'a', 's', 34 ]
compact(null) // []Performs right-to-left function composition.
Kind: global function
Signature: compose :: [(m -> n), ..., (b -> c), (a -> b)] -> a -> n
Example
const addOne = x => x + 1;
const timeTen = x => x * 10;
const addOneTimeTen = compose(timeTen, addOne);
const result = addOneTimeTen(9); // 100Concatenates two String|Arrays together. Returns empty array if value arent of the same type or not String|Array.
Kind: global function
Signature: concat :: a -> b -> c
Example
concat('foo', 'bar') // foobar
concat([1, 2], [3, 4]) // [1, 2, 3, 4]Concatenates N Arrays together.
Kind: global function
Signature: concat :: [a] -> [b] -> ...[n] -> [m]
Example
concatN([1, 2], [3, 4], [5, 6]) // [1, 2, 3, 4, 5, 6]Wraps the given function, if the number of provided args is sufficient, call the passed function fn. Otherwise, return a wrapped function fn that expects the rest of the arguments. If you want to curry a function that accepts a variable number of arguments (a variadic function), you can optionally pass the number of arguments to the second parameter arity.
Kind: global function
Signature: curry :: ((a, b, ..., n) -> m) -> a -> b -> ...n -> m
Example
const add = curry((x, y) => x + y);
const addFiveTo = add(5);
addFiveTo(10); // 15Returns the difference between two arrays.
Kind: global function
Signature: difference :: [a] -> [b] -> [c]
Example
difference([ 1, 2, 3 ], [ 1, 2, 4 ]) // [3]
difference([], [ 1, 2, 4 ]) // [ 1, 2, 4 ]
difference([ 1, 2, 3 ], []) // [ 1, 2, 3 ]
difference([ 1, 2, 3 ], null) // [ 1, 2, 3 ]Returns all of the distinct values of an array.
Kind: global function
Signature: distinct :: [a] -> [b]
Example
distinct([ 1, 2, 2, 3, 4, 4, 5 ]) // [ 1, 2, 3, 4, 5 ]Returns all of the distinct values of the given arrays.
Kind: global function
Signature: distinctN :: [a] -> [b] -> ...[n] -> [m]
Example
distinctN([ 1, 2 ], [ 2, 3, 4 ], [ 4, 5 ]) // [ 1, 2, 3, 4, 5 ]Applies the given func to each element in the array.
Kind: global function
Signature: each :: (a -> b) -> [c] -> undefined
Example
difference(log, [1, 2, 3])Determines if all element in an array satisfy the given test function
Kind: global function
Signature: every :: (a -> Bool) -> [a] -> Bool
Aka: all
Example
every(Boolean, [1, 2, 3, 4]) // true
every(Boolean, [1, 2, null, 4]) // falseFilters the array using the given function.
Kind: global function
Signature: filter :: (a -> Boolean) -> [a] -> [a]
Example
filter(x => x > 5, [1, 2, 3, 5, 6, 7]) // [6, 7]Finds the first element that satisfies the given test func.
Kind: global function
Signature: find :: (a -> Boolean) -> [a] -> a
Example
find(x => x.score === 5, [{score: 1}, {score: 2}, {score: 5}, {score: 6}, {score: 7}]) // {score: 5}Flattens single nested array.
Kind: global function
Signature: flatten :: [a] -> [a]
Example
flatten([[ 1, 2 ], [ 3, 4 ]];); // [ 1, 2, 3, 4 ]
flatten(null) // []Determines if the given value is an array.
Kind: global function
Signature: isArray :: a -> Boolean
Example
isArray([1, 2, 3]) // true
isArray({ a: 'b' }) // falseDetermines if the given value is a function.
Kind: global function
Signature: isFunction :: a -> Boolean
Example
isFunction(() => {}) // true
isFunction([1, 2, 3]) // falseDetermines if the given value is a number.
Kind: global function
Signature: isNumber :: a -> Boolean
Example
isNumber(42) // true
isNumber(8e5) // true
isNumber(0x2F) // true
isNumber('foo bar') // falseDetermines if the given value is an object.
Kind: global function
Signature: isObject :: a -> Boolean
Example
isObject({ a: 'b' }) // true
isObject([1, 2, 3]) // falseDetermines if the given value is a string.
Kind: global function
Signature: isString :: a -> Boolean
Example
isString('foo bar') // true
isString({ a: 'b' }) // falseNegates the given boolean-like value.
Kind: global function
Signature: not :: Boolean -> Boolean
Example
not(true); // false
not(false); // true
not(2); // falseCalls the given function with the given value and returns the value.
Kind: global function
Signature: tap :: (a -> b) -> a -> a
Example
tap(console.log, 'foobar') // foobarFJP is licensed under the MIT license.
Copyright © 2018 Bryan Kizer