Error Monad and Monad Transformer for Akh Javascript Monad Library

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

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

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

Usage

The ErrorT and Error implement the Fantasy Land monad, functor, and applicative functor interfaces.

// Error monad
require('akh.error').Error
require('akh').Error

// Error monad transformer
require('akh.error').ErrorT
require('akh').ErrorT

Error.run(m, ok, err), m.run(ok, err)

Perform a error computation m and invoke ok if it succeeds and err if it fails.

const c =
    Error.of(3)
        .map(x => -x);

Error.run(c, console.error, console.log); // logs: -3

ErrorT.run(t, ok, err), t.run(ok, err)

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

Error.attempt(m, def), m.attempt(def)

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

Error.try(m, e), m.try(e)

Perform an error computation m and return the result if it succeeds and invoke e if it fails

Error Interface

Error.fail(x)

ErrorT(m).fail(x)

Construct a error value value.

Error.handle(f)

ErrorT(m).handle(f)

Handle an error.

Contributing

Contributions are welcome.

To get started:

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

ChangeLog

0.0.1 - September 2, 2016

• Fixing m.run interfaces.

0.0.0 - September 1, 2016

• Initial release.