chrisdone

{-# LANGUAGE TemplateHaskell #-}
-- | For when you have a record that doesn't have lenses derived for
-- it and you need a lens, just use @$(lens 'thefield)@ and away you go.
module Control.Lens.FieldTH where
import Language.Haskell.TH
lens :: Name -> Q Exp
lens name = do
  [|\f r ->
      fmap
        $(lamE

ndmitchell

This is intended as a reply to https://ro-che.info/articles/2017-06-12-friendly-contributing-policies, but I don't really want it to be a blog post (it's not the right level for my blog), and that blog doesn't have comments, and I don't want to mis-express myself in 120 characters or whatever. So here goes a gist :)

Firstly, as to the talk, the context was read around the project, and figure out if it will suit you. I am deliberately quoting haskell-src-exts out of context, and deliberately not saying where either quote came from. I appreciate the full policy is much more welcoming than that one snippet would imply.

However, when I wanted to find an unfriendly contributing policy, I immediately thought of haskell-src-exts. I do genuinely find the document, as a whole, quite unwelcoming. I appreciate that languages sound different to native speakers, and it didn't stop me contributing, but it did give me pause. Whether a document is friendly or not is a feeling, and so by explaining why I have that feeling

aaronlevin

{-# LANGUAGE OverloadedStrings #-}

module Main where

import Network.Wai (pathInfo, Request, requestMethod, Response, responseLBS, ResponseReceived)
import Network.Wai.Handler.Warp (run)
import Network.HTTP.Types (status200, status401)

-- note: type Application = Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived
application :: Request -> (Response -> IO ResponseReceived) -> IO ResponseReceived

Profpatsch

#!/usr/bin/env bash

if [[ -z "$1" ]]; then
  echo "No filter given, abort"
  exit 1
fi

tmp=$(mktemp -d)
jq="$tmp/jq"

thumphries

{-# LANGUAGE TemplateHaskell #-}
module Lens where

import Control.Lens
import Data.Monoid (First, (<>))

data FooBar =
     Foo (Either Int Bool)
   | Bar (Maybe Bool)

chrisdone

{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -Wall #-}

-- Set your font to a monospace font which makes this character the same as the line-height: │
--
-- Otherwise, you'll see an ugly gap between connected lines if the
-- line-height of the font is high.
--
-- Example fonts:
--

Porges

The original code (~7.2s on my laptop).

import System.Random
import System.CPUTime

rainfall :: [Int] -> Int
rainfall xs = sum (zipWith (-) mins xs)

VictorTaelin

This is a term that performs modulo 32 addition on two 32-bit binary numbers efficiently on the abstract algorithm.

On this example, I compute 279739872 + 496122620 = 775862492.

binSize= 32
binZero= (binSize r.a.b.c.(a r) a.b.c.c)
binSucc= (binSize r.x.a.b.c.(x b x.(a (r x)) c) a.a)
binFold= x.a.b.c.(binSize r.x.(x x.f.(a (f x)) x.f.(b (f x)) f.c r) a.c x)
binToNat= (binSize r.n.x.(x x.f.(f x) x.f.(add n (f x)) f.0 (r (mul 2 n))) n.x.0 1)

mpickering

How to test your package with ghc-8.6.1

1. Setup the binary cache -

cachix use mpickering

For only GHC

frasertweedale

{-# LANGUAGE RankNTypes #-}

import Numeric.Natural (Natural)
import Numeric.AD (diff)

newtonRoot
  :: (Floating a, Ord a)
  => Natural  -- ^ iterations
  -> a        -- ^ epsilon
  -> a        -- ^ starting guess