do-list: Do notation for free

[ bsd3, data, library, list, syntax ] [ Propose Tags ]

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Versions [RSS] 0.8.0, 0.8.1, 0.9.0, 0.9.1, 1.0.0, 1.0.1
Change log changelog.md
Dependencies base (<5) [details]
License BSD-3-Clause
Copyright 2016 Taras Serduke
Author Taras Serduke
Maintainer taras.serduke@gmail.com
Category Data, List, Syntax
Home page https://github.com/tserduke/do-list#readme
Bug tracker https://github.com/tserduke/do-list/issues
Source repo head: git clone https://github.com/tserduke/do-list.git
Uploaded by TarasSerduke at 2016-09-19T10:11:19Z
Distributions LTSHaskell:1.0.1, NixOS:1.0.1, Stackage:1.0.1
Reverse Dependencies 1 direct, 0 indirect [details]
Downloads 4681 total (23 in the last 30 days)
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Readme for do-list-1.0.1

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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