mattbierner / akh-maybe

Akh maybe monad transformer and monad

Maybe Monad and Monad Transformer for Akh Javascript Monad Library

The MaybeT transformer, MaybeT, adds error control to a monad. The base type, Maybe, provides error logic on its own.

# To use as standalone package
$ npm install --save akh.maybe

# To use as part of akh library
$ npm install --save akh

Usage

MaybeT and Maybe implement the Fantasy Land monad, functor, and applicative functor interfaces.

// Maybe monad
require('akh.maybe').Maybe
require('akh').Maybe

// Maybe monad transformer
require('akh.maybe').MaybeT
require('akh').MaybeT

Maybe.run(m), m.run()

Perform a error computation m and return a maybe object result

Maybe.run(Maybe.just(3).map(x => -x)) === { just: true, value: -3 }
Maybe.run(Maybe.nothing.map(x => -x)) === { nothing: true }

MaybeT.run(t), t.run()

Same as Maybe.run but for a monad transformer. Returns an Maybe value inside of the inner monad.

Maybe.maybe(m, def), m.maybe(def)

Perform an maybe computation m and return the result if it succeeds and def if it fails.

Maybe Interface

Maybe.just(x)

MaybeT(m).just(x)

Same as Maybe.of. Success value.

Maybe.nothing

MaybeT(m).nothing

Error value

Contributing

Contributions are welcome.

To get started:

$ cd akh-maybe
$ npm install # install dev packages
$ npm test # run tests