Monads

A monad is a versatile functor that adheres to the laws of associativity, left-identity, and right-identity. The monads available as part of bingo-functional's offering include IO, State, Reader, List, Writer, Either, and Maybe. Monads, like other non Composite Data Type artifacts, are manipulable via function primitives. To follow is an elaborate listing of useful monad helper functions/primitives.

bind

bind(function, monad)

bind :: Monad m => m a -> (a -> m b) -> m b

Sequentially composes two actions, passing any value produced by the first as an argument to the second. Akin to the >>= operator in Haskell.

Since:

• bingo-functional - v1.11.0
• bingo-functional-js - v0.1.0

Argument(s):

• function - A Monadic function
• monad - An instance of a Monad

JavaScript

import { bind, reader, concat, partial } from 'bingo-functional-js'
const res = bind(  (greet) =>    reader((name) =>      concat('', greet, '.', name === 'world' ? '' : ' How are you?'),    ),  reader(partial(concat, ' ', 'Hello,')),)
res.run('Loki')

PHP

use function Chemem\Bingo\Functional\Functors\Monads\bind;use Chemem\Bingo\Functional\Functors\Monads\Reader;
$res = bind(  fn (string $greet) => Reader\reader(fn (string $name) => (    f\concat('', $greet, '.', $name === 'world' ? '' : ' How are you?')  )),  Reader\reader(f\partial(f\concat, ' ', 'Hello,')));
$res->run('Loki');

mcompose

mcompose(...functions)

mcompose :: m a -> n s -> n a

Composes two monadic operations from right to left.

Since:

• bingo-functional - v1.11.0
• bingo-functional-js - v0.1.0

Argument(s):

• function - A Monadic function

JavaScript

import { mcompose, State } from 'bingo-functional-js'
const res = mcompose(  (x) => State.of(x ** 3),  (x) => State.of(x ** 2),)
res(State.of(2)).run('square then cube')

PHP

use function Chemem\Bingo\Functional\Functors\Monads\mcompose;use Chemem\Bingo\Functional\Functors\Monads\State;
$res = mcompose(  fn (int $x) => State::of($x ** 3),  fn (int $x) => State::of($x ** 2),);
$res(State::of(2))->run('square then cube');

foldM

foldM(function, list, accumulator)

foldM :: (a -> b -> m a) -> [b] -> c -> m b

Analogous to fold except its result is encapsulated within a monad.

Since:

• bingo-functional - v1.12.0
• bingo-functional-js - v0.1.0

Argument(s):

• function - A Monadic fold function
• list - Arbitrary list to transform
• accumulator - The accumulator value

JavaScript

import { foldM, IO } from 'bingo-functional-js'
const maxM = foldM(  (acc, val) => IO(() => (val > acc ? val : acc)),  [4, 12, 23, 2, 19],  0,)

PHP

use function Chemem\Bingo\Functional\Functors\Monads\foldM;use Chemem\Bingo\Functional\Functors\Monads\IO;
$maxM = foldM(  fn ($acc, $val) => IO\IO(fn () => $val < $acc ? $val : $acc),  [4, 12, 23, 2, 19],  0);

filterM

filterM(function, list)

filterM :: (a -> m a) -> [a] -> m [a]

Analogous to filter except its result is encapsulated within a monad.

Since:

• bingo-functional - v1.12.0
• bingo-functional-js - v0.1.0

Argument(s):

• function - A Monadic filter function
• list - Arbitrary list to transform

JavaScript

import { filterM, fromValue } from 'bingo-functional-js'
const evenM = filterM((x) => fromValue(x % 2 === 0), [4, 12, 23, 2, 19])

PHP

use function Chemem\Bingo\Functional\Functors\Monads\filterM;use Chemem\Bingo\Functional\Functors\Monads\IO;
$evenM = filterM(  fn (int $x) => IO\IO(fn () => $x % 2 == 0),  [4, 12, 23, 2, 19],);

mapM

mapM(function, list)

mapM :: (a -> m b) -> [a] -> m [b]

Analogous to map except its result is encapsulated within a monad.

Since:

• bingo-functional - v1.13.0
• bingo-functional-js - v0.1.0

Argument(s):

• function - A transformative function
• list - Arbitrary list to transform

JavaScript

import { mapM, writer } from 'bingo-functional-js'
const squares = mapM((x) => writer(x ** 2, `square ${x}`), [3, 9, 12])

PHP

use function Chemem\Bingo\Functional\Functors\Monads\mapM;use Chemem\Bingo\Functional\Functors\Monads\IO;
$uppercase = mapM(  fn (string $str) => IO\IO(fn () => strtoupper($str)),  ['foo', 'bar', 'baz'],);

liftM

liftM(function, ...args)

liftM :: Monad m => (a -> r) -> m a -> m r

Promotes a function to a monad.

Since:

• bingo-functional - v2.0.0

Argument(s):

• function - An arbitrary function
• args - Monad-encapsulated function arguments

use function Chemem\Bingo\Functional\Functors\Monads\liftM;use Chemem\Bingo\Functional\Functors\Monads\State;
$msquare = liftM(fn ($x) => $x ** 2, State::of(3));