exceptional

Essentially the Maybe type with error messages.

https://github.com/pharpend/exceptional

Version on this page:0.1.3.0
LTS Haskell 14.27:0.3.0.0
Stackage Nightly 2019-09-21:0.3.0.0
Latest on Hackage:0.3.0.0

See all snapshots exceptional appears in

BSD-2-Clause licensed by Peter Harpending
Maintained by [email protected]
This version can be pinned in stack with:exceptional-0.1.3.0@sha256:7391f5c9e2c1c7ec9fe20b98361843936df037f98bbe22beb507b51623b54fa8,1907

Module documentation for 0.1.3.0

Depends on 1 package(full list with versions):
base

exceptional

This is a Haskell library that exists to house a type:

data Exceptional x
  = Failure String
  | Success x

It’s much like Maybe, except instead of Nothing, we have Failure String.

A comparison could also be made to Either String. I made this library because I was dissatisfied with the Monad instance for Either. In this type, fail = Failure. It’s rather simple.

Installing

cabal install exceptional

Or, add exceptional to the build-depends field in your .cabal file.