polyvariadic: Creation and application of polyvariadic functions

[ bsd3, data, library ] [ Propose Tags ]

Creation and application of polyvariadic functions, see the docs for usage and examples


[Skip to Readme]
Versions 0.3.0.0, 0.3.0.1, 0.3.0.2, 0.3.0.3 (info)
Change log ChangeLog.md
Dependencies base (>=4.7 && <4.12), containers (>=0.1 && <0.6), semigroups (==0.18.*) [details]
License BSD-3-Clause
Copyright (C) Francesco Gazzetta 2017
Author Francesco Gazzetta
Maintainer francygazz@gmail.com
Revised Revision 1 made by fgaz at Fri May 25 12:19:24 UTC 2018
Category Data
Home page https://github.com/fgaz/polyvariadic
Source repo head: git clone git://github.com/fgaz/polyvariadic.git
Uploaded by fgaz at Tue Dec 19 17:37:54 UTC 2017
Distributions NixOS:0.3.0.3
Downloads 765 total (22 in the last 30 days)
Rating 2.0 (votes: 1) [estimated by rule of succession]
Your Rating
  • λ
  • λ
  • λ
Status Docs available [build log]
Last success reported on 2017-12-19 [all 1 reports]
Hackage Matrix CI

Modules

[Index]

Downloads

Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.

Maintainer's Corner

For package maintainers and hackage trustees


Readme for polyvariadic-0.3.0.3

[back to package description]

polyvariadic

Creation and application of polyvariadic functions

Build Status Hackage

For example, the classic printf:

{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FlexibleContexts #-}
import Data.Function.Polyvariadic
import Data.Accumulator

magicChar = '%'
notMagicChar = (/= magicChar)

data PrintfAccum = PrintfAccum { done :: String, todo :: String }

instance Show x => Accumulator PrintfAccum x where
  accumulate x (PrintfAccum done (_:todo)) = PrintfAccum
                                              (done ++ show x ++ takeWhile notMagicChar todo)
                                              (dropWhile notMagicChar todo)
  accumulate _ acc = acc

printf' str = polyvariadic
               (PrintfAccum (takeWhile notMagicChar str) (dropWhile notMagicChar str))
               done
>>> printf' "aaa%bbb%ccc%ddd" "TEST" 123 True
"aaa\"TEST\"bbb123cccTrueddd"