README

Functional utils

Examples:

use Kikytokamuro\Futils\Func;
use Kikytokamuro\Futils\Monad;

All

Determines whether all elements of the array satisfies the predicate.

Func::all(fn($x) => $x > 100)([101, 102, 103]) // => true

Always

Creates a function that always returns a given value.

Func::always(true)() // => true

Any

Determines whether any element of the array satisfies the predicate.

Func::any(fn($x) => $x == 100)([1, 2, 100]) // => true

Compose

Function composition (fn -> ... -> f2 -> f1).

Func::compose(fn($x) => $x + 1, fn($x) => $x * 100)(2) // => 201

Contains

Check whether a value is contained in a array.

Func::contains(1337)([1, 1337, 2]) // => true

Chunk

Split an array into chunks of the given size.

Func::chunk(2)([1, 2, 3, 4, 5]) // => [[1, 2], [3, 4], [5]]

Difference

Computes the difference of arrays.

Func::difference([1, 2, 3, 4])([1, 2]) // => [3, 4]

Drop

Drops the first n elements off the front of the array.

Func::drop(2)([1, 2, 3, 4]) // => [3, 4]

Filter

Filters elements of an array using a callback function.

Func::filter(fn($x) => $x > 0)([-1, -2, 1, 2]) // => [1, 2]

Find

Find first element of the array satisfies the predicate.

Func::find(fn($x) => $x > 10)([1, 2, 11]) // => 11

Flatten

Flattens nested arrays.

Func::flatten([1, [2, [3, [4]]]]) // => [1, 2, 3, 4]

Has

Check if exists element with this key in array.

Func::has("test")(["test" => 1]) // => true

Head

Get head of array.

Func::head([1, 2, 3]) // => 1

IndexOf

Get first index of value in array.

Func::indexOf("test")([1, "test", 3]) // => 1

Intersection

Computes the intersection of arrays.

Func::intersection([1, 2, 3, 4])([2, 3, 5]) // => [2, 3]

Join

Join array elements with a string.

Func::join([1, 2, 3])("|") // => "1|2|3"

Last

Get last element of array.

Func::last([1, 2, 3, 4]) // => 4

Map

Applying function to each element of array.

Func::map(fn($x) => $x + 1)([1, 2, 3]) // => [2, 3, 4]

Memoize

Creates a memoized version of a function that caches results by arguments.

$fn = Func::memoize(fn($x) => $x * 1000);
$fn(5); // => calculates and caches
$fn(5); // => returns cached result

Merge

Merge two arrays.

Func::merge([1, 2])([3, 4]) // => [1, 2, 3, 4]

Omit

Returns an array without the specified keys.

Func::omit(['b'])(['a' => 1, 'b' => 2, 'c' => 3]) // => ['a' => 1, 'c' => 3]

Partial

Create partial function.

Func::partial(fn($x, $y, $z) => $x + $y + $z)(1, 2)(3) // => 6

Pick

Returns an array with only the specified keys.

Func::pick(['a', 'c'])(['a' => 1, 'b' => 2, 'c' => 3]) // => ['a' => 1, 'c' => 3]

Partition

Equivalent to [(filter f, arr), (reject f, arr)]

Func::partition(fn($x) => $x > 0)([-1, -2, 1, 2]) // => [[1, 2], [-1, -2]]

Pipe

Function composition (f1 -> f2 -> ... -> fn).

Func::pipe(fn($x) => $x + 1, fn($x) => $x * 100)(1) // => 200

Reduce

Reduce the array to a single value using a callback function.

Func::reduce(fn($x, $y) => $x + $y)([1, 2, 3]) // => 6

Reject

Like filter, but the new array is composed of all the items which fail the function.

Func::reject(fn($x) => $x > 0)([-1, -2, 1, 2]) // => [-1, -2]

Replace

Replaces elements from passed arrays into the first array.

Func::replace([1, 2, 3])([1 => 3, 2 => 2]) // => [1, 3, 2]

Tail

Get tail of array

Func::tail([1, 2, 3, 4, 5]) // => [2, 3, 4, 5]

Once

Creates a function that is restricted to invoking the given function once.

$init = Func::once(fn() => doSomething());
$init(); // => executes
$init(); // => returns cached result, no execution

Tap

Invokes the interceptor and returns the value.

Func::tap(fn($x) => log($x))($value) // => returns $value, calls log($x) as side effect

Take

Get n first elements from array.

Func::take(2)([1, 2, 3, 4]) // => [1, 2]

Union

Computes the union of arrays (with deduplication).

Func::union([1, 2, 3])([3, 4, 5]) // => [1, 2, 3, 4, 5]

When

Only when predicate is true then appling function to argument, else return argument.

Func::when(fn($x) => $x > 100)(fn($x) => $x + 5)(1000) // => 1005

Zip

Zips together its two arguments into a array of arrays.

Func::zip([1, 2, 3])([4, 5, 6]) // => [[1, 4], [2, 5], [3, 6]]

Monads

IdentityMonad - Just annotates plain values and functions to satisfy the monad laws.

(new Monad\IdentityMonad(100))
    ->bind(fn($x, $n) => $x * $n, 2)
    ->bind("strval")
    ->extract() // => "200"

MaybeMonad - Encapsulates the type of an undefined value.

(new Monad\MaybeMonad("test"))
    ->bind(fn() => null)
    ->bind(fn($x) => $x + 1)
    ->extract() // => null

ListMonad - Abstracts away the concept of a list of items.

(new Monad\ListMonad([1, new Monad\IdentityMonad(2), new Monad\MaybeMonad(3), new Monad\ListMonad([4])]))
    ->bind(fn($x) => $x + 100)
    ->extract() // => [101, 102, 103, [104]]

EitherMonad - Represents a value of one of two possible types (Left or Right). Right is the "success" case, Left is the "failure" case.

Monad\EitherMonad::right(10)
    ->bind(fn($x) => $x * 2)
    ->bind(fn($x) => $x > 15 ? Monad\EitherMonad::right($x) : Monad\EitherMonad::left("Too small"))
    ->fold(
        fn($err) => "Error: $err",
        fn($val) => "Success: $val"
    ); // => "Success: 20"

Monad\EitherMonad::left("error")
    ->bind(fn($x) => $x * 2)
    ->extract(); // => "error"

TryMonad - Represents a computation that may either result in an exception (Failure) or return a successfully computed value (Success).

Monad\TryMonad::of(fn($json) => json_decode($json, true), '{"a":1}')
    ->bind(fn($data) => $data['a'])
    ->recover(fn($e) => null)
    ->extract(); // => 1

Monad\TryMonad::of(fn() => throw new \RuntimeException("error"))
    ->bind(fn($x) => $x * 2)
    ->getOrElse("default"); // => "default"

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