bitemyapp

The Learning Haskell guide has been moved to a git repo to enable outside contribution

Find it here: https://github.com/bitemyapp/learnhaskell

david-christiansen

module Test

import Provider

import Database
import Queries

%language TypeProviders

%link C "sqlite3api.o"

gelisam

-- in reply to http://www.reddit.com/r/haskell/comments/21mja6/make_lllegal_state_transitions_unrepresentable/
-- 
-- We implement a tiny language with three commands: Open, Close, and Get.
-- The first Get after an Open returns 1, the second Get returns 2, and so on.
-- 
-- Get is only valid while the state is open, and
-- Open must always be matched by a Close.
-- We enforce both restrictions via the type system.
-- 
-- There are two valid states: Opened and Closed.

richp10

// This systemd runs iptables-restore on boot:
[Unit]
Description=Packet Filtering Framework
DefaultDependencies=no
After=systemd-sysctl.service
Before=sysinit.target

[Service]
Type=oneshot
ExecStart=/usr/sbin/iptables-restore /opt/docker/scripts/iptables/iptables.rules

begriffs

This is a preview of Tom Ellis' database query library for Haskell.

> {-# LANGUAGE Arrows, FlexibleContexts #-}
> -- TODO: Get rid of FlexibleContexts if we ever move the definition of s
> --    elsewhere.
> {-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
> {-# LANGUAGE TemplateHaskell #-}
>
> module Karamaan.Opaleye.Examples where
>

gelisam

In response to this reddit post about failing to understand the Pipes library after a couple of hours. I wanted to show how an experienced haskeller does it, but I'm afraid it also took me quite a few hours, which is why the following list of steps goes on and on.

After all those hours, my opinion is that Pipes is not at all an easy library. I don't know if Conduit is any easier, but otherwise I side with your friend in advising to use something else (perhaps ordinary lazy IO?) instead of Pipes.

Anyway, here is the full brain dump of my steps as I tried to get your three snippets to fit together.

• Since you say that you have a hard time combining the snippets, I assume that they must have complicated types. So my first goal is to figure out the type of your first snippet.
• hoogle for parseUrl, withManager, etc. No results.
• Google for haskell runEffect, find that it's a method from Pipes.Core,

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

david-christiansen

module FizzBuzzC

%default total

-- Dependently typed FizzBuzz, constructively

-- A number is fizzy if it is evenly divisible by 3
data Fizzy : Nat -> Type where
  ZeroFizzy : Fizzy 0
  Fizz : Fizzy n -> Fizzy (3 + n)

gtani7

http://www.jerf.org/iri/post/2908
http://mwotton.github.com/hs_gbu/
http://reddit.com/r/haskell/comments/y6i7d/do_we_have_real_world_examples_of_where_static/
http://reddit.com/r/haskell/comments/12e3a0/the_good_the_bad_and_the_ugly_haskell_in/

http://blog.codersbase.com/2010/09/composability-laziness-testing-and.html
https://www.fpcomplete.com/user/imalsogreg/functional-programming-elevator-pitch
http://evincarofautumn.blogspot.com/2012/07/so-i-write-compilers-for-living-now.html
http://www.reddit.com/r/haskell/comments/2gz7s1/please_point_me_at_an_eloquent_paper_or_post_on/

gerardroche

name: Pacific/Kiritimati              , cc: KI        , offset: 50400 (14 hours)         , comments: Line Islands
name: Pacific/Chatham                 , cc: NZ        , offset: 49500 (13.75 hours)      , comments: Chatham Islands
name: Pacific/Fakaofo                 , cc: TK        , offset: 46800 (13 hours)         , comments:
name: Antarctica/South_Pole           , cc: AQ        , offset: 46800 (13 hours)         , comments: Amundsen-Scott Station, South Pole
name: Antarctica/McMurdo              , cc: AQ        , offset: 46800 (13 hours)         , comments: McMurdo Station, Ross Island
name: Pacific/Tongatapu               , cc: TO        , offset: 46800 (13 hours)         , comments:
name: Pacific/Enderbury               , cc: KI        , offset: 46800 (13 hours)         , comments: Phoenix Islands
name: Pacific/Apia                    , cc: WS        , offset: 46800 (13 hours)         , comments: