do-list

Do notation for free https://github.com/tserduke/do-list#readme

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BSD-3-Clause licensed by Taras Serduke

do-list do-list do-list

Do notation for free.

Summary

do-list makes it easy to use do notation. You can construct lists or monoids using DoList or DoMonoid modules respectively. do-list is designed to work well with OverloadedStrings and OverloadedLists extensions. See examples.

As alternative there is a canonical Writer without overloading support.

Examples

Benchmarks

{-# LANGUAGE OverloadedLists #-}

module Main (main) where

import Criterion.Main
import Data.DoList (DoList, item, toList)

main :: IO ()
main = defaultMain $ toList $ do
  doBench "add"  $ whnf (2 +) (1 :: Int)
  doBench "sub" $ whnf (2 -) (1 :: Int)
  -- Regular criterion benchmarks are injected via list overloading
  [multBench, divBench]

multBench, divBench :: Benchmark
multBench = bench "mult" $ whnf (2 *) (2 :: Int)
divBench = bench "div" $ whnf (2 `div`) (2 :: Int)

-- Now we can define benchmarks with do notation.
doBench :: String -> Benchmarkable -> DoList Benchmark
doBench name = item . bench name

Multiline Text

{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-unused-do-bind #-}

module Main (main) where

import Data.DoMonoid (runDoM)
import Data.Text.IO as T (putStr)

main :: IO ()
main = T.putStr $ runDoM $ do
  -- Lines are combined using Text.append
  "fib 0 = 0\n"
  "fib 1 = 1\n"
  "fib n = fib (n-1) + fib (n-2)\n"

Indentation

{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-unused-do-bind #-}

module Main (main) where

import Data.DoList (DoList, fromList, toList)
import Data.Text as T (Text, append, unlines)
import Data.Text.IO as T (putStr)

main :: IO ()
main = T.putStr $ T.unlines $ toList $ do
  "Here goes indented list:"
  indent $ do
    "1. Item 1"
    indent $ do
      "* Item a"
      "* Item b"
    "2. Item 2"
    "3. Item 3"

indent :: DoList Text -> DoList Text
-- fromList and toList are no-ops
indent = fromList . map (append "  ") . toList

Changes

Change Log

1.0.1 (2016-09-19)

  • Links to Stackage in readme
  • Minor cabal package fixes

1.0.0 (2016-09-12)

  • Added DoMonoid with IsString and IsList instances
  • Replaced DList with DoMonoid for DoList -> better performance
  • Removed toDList function
  • Removed dependency on dlist
  • Added more usage examples
  • Better readme
  • More benchmarks
  • Documentation edits
  • Added Hackage badge

0.9.1 (2016-09-10)

  • IsList instance
  • More bechmarks

0.9.0 (2016-09-08)

  • Changed back result type of item to polymorphic
  • Added IsString instance
  • Renamed unDoList to toDList
  • Documentation edits
  • Added benchmarks

0.8.1 (2016-09-07)

  • Reified result type of item to ()
  • Added note about Control.Monad.Writer
  • Minor documentation edits