Popularity
6.9
Growing
Activity
0.0
Stable
16
3
4

Monthly Downloads: 3
Programming language: Haskell
License: MIT License
Tags: Constraints     Utils    
Latest version: v0.1.2

constraints-emerge alternatives and similar packages

Based on the "Constraints" category

Do you think we are missing an alternative of constraints-emerge or a related project?

Add another 'Constraints' Package

README

constraints-emerge: defer instance lookups until runtime

Build Status | Hackage

Dedication

Failure should be our teacher, not our undertaker. Failure is delay, not defeat. It is a temporary detour, not a dead end. Failure is something we can avoid only by saying nothing, doing nothing, and being nothing.

Denis Waitley

Synopsis

{-# LANGUAGE ConstraintKinds     #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications    #-}
{-# OPTIONS_GHC -fplugin=Data.Constraint.Emerge.Plugin #-}

module Test where

import Data.Constraint.Emerge

showAnything :: forall c. Emerge (Show c) => c -> String
showAnything c =
  case emerge @(Show c) of
    Just Dict -> show c
    Nothing -> "<<unshowable>>"


showBool = showAnything True  -- "True"
showId   = showAnything id    -- "<<unshowable>>"

Known Bugs

  • constraints-emerge will fail to generate type-equality dictionaries
  • It fails to provide Emerge c dictionaries at runtime.
  • The generated error messages mention mangled type variables; it would be cool if they didn't.

If someone wants to pick it up from here, that’d be great!

Contact

Please reports bugs and missing features at the GitHub bugtracker. This is also where you can find the source code.

constraints-emerge was written by Sandy Maguire and is licensed under a permissive MIT license.


*Note that all licence references and agreements mentioned in the constraints-emerge README section above are relevant to that project's source code only.