tonyday567

{-# LANGUAGE ExistentialQuantification, RankNTypes #-}

module Scanl where

import           Control.Foldl (Fold(..))
import           Data.Foldable (Foldable)
import qualified Data.Foldable as F
import           Data.Traversable

scan :: (Foldable f) => Fold a b -> f a -> [b]

tonyday567

body {
  font-family: Helvetica, arial, sans-serif;
  font-size: 14px;
  line-height: 1.6;
  padding-top: 10px;
  padding-bottom: 10px;
  background-color: white;
  padding: 30px; }

body > *:first-child {

tonyday567

literate haskell test

> {-# LANGUAGE RankNTypes, KindSignatures #-}

> module ArcChallenge where
>
> import Control.Applicative

> module ArcChallenge where
>

tonyday567

In this gist we will first show that we can beat the arc challenge
(http://www.paulgraham.com/arcchallenge.html), and then build the library that
shows how we did it. This gist is Literate Haskell and is of course executable. The packages needed are happstack-server and applicative-extras, installable using cabal.

Let's start with some imports (for now, you can ignore these)

> {-# LANGUAGE GADTs, TypeSynonymInstances #-}
> module ArcChallenge where
>
> import Control.Applicative

tonyday567

bird
----

> {-# LANGUAGE GADTs, TypeSynonymInstances #-}
> module ArcChallenge where
>
> import Control.Applicative
> import Control.Applicative.Error (Failing (..))
> import Control.Monad (ap)

tonyday567

{-# LANGUAGE Arrows #-}

import           Prelude hiding ((.), id)

import           Control.Arrow (Arrow(arr, first), ArrowChoice(left))
import           Control.Category (Category((.), id))
import           Control.Foldl
import           Control.Monad ((>=>))
import           Control.Monad.Trans.State.Strict (get, put)
import           Pipes

tonyday567

{-# LANGUAGE RankNTypes #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures -fno-warn-type-defaults -fno-warn-unused-do-bind -fno-warn-unused-imports -fno-warn-orphans #-}

--
-- Random walk emitter with go and stop button
--

module Main where

import           Control.Applicative

tonyday567

module Main where

import Control.Concurrent hiding (yield)
import Control.Concurrent.Chan
import Data.Char (chr)
import Data.Maybe
import Control.Monad
import Control.Monad.Random ( RandomGen, Rand, getRandomR, evalRandIO)
import Control.Monad.Trans.State.Strict (StateT, get, put, evalStateT)
import Data.List

tonyday567

{-# LANGUAGE ExistentialQuantification #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures -fno-warn-type-defaults -fno-warn-unused-do-bind -fno-warn-unused-imports -fno-warn-orphans #-}

module Main where

import Control.Applicative
import Data.List (foldl')
import Data.Monoid
import Data.Strict.Tuple
import Prelude hiding (sum, length)

tonyday567

{-# LANGUAGE ScopedTypeVariables, OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures -fno-warn-type-defaults -fno-warn-unused-do-bind #-}

{-| Testing basic interaction between

  - StateT
  - Pipes, and
  - tcp server concepts
  - using inner pipes (pipes within another pipe component with a wider context)
-}