gatlin

#lang r5rs
; Composable syntax-rules macros via the CK abstract machine
;
; We demonstrate (mutually-) recursive, higher-order applicative
; macros with clausal definitions, defined in the style that looks very 
; much like that of ML or (strict) Haskell.
; We write composable, call-by-value--like macros without
; resorting to the continuation-passing-style and thus requiring no 
; macro-level lambda. The syntax remains direct-style, with 
; nested applications.

gatlin

#!/usr/bin/env bash

###
# Usage
###
#     twitch <path-to-file>

PATH_TO_TWITCH_KEY="$HOME/.config/twitch.key"
if [ ! -f "$HOME/.config/twitch.key" ]; then
    echo "Please write your twitch key to $PATH_TO_TWITCH_KEY"

gatlin

{- |
Operational transformation in Haskell using (co)free (co)monads.
-}

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}

import Data.List (splitAt)
import Control.Monad

gatlin

class cont:

    def __init__(self, fn):
        self.fn = fn

    def __call__(self, *args, **kwargs):
        return (lambda: self.fn(*args, self, **kwargs))

class tailrec:

gatlin

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE DeriveFoldable #-}
{-# LANGUAGE DeriveTraversable #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}

gatlin

/* Helper function which writes a string to a file descriptor.
*/
static gboolean
write_to_fd (int fd, const gchar *message) {
  gsize bw;
  GIOChannel *channel = g_io_channel_unix_new (fd);
  GString *message_str = g_string_new (message);
  g_string_append (message_str, "\n");
  g_io_channel_write_chars (channel,
                            message_str->str,

gatlin

It's said that all Haskell programmers eventually write a blog post explaining
Monads. Today I fulfill my destiny. The basic format is ripped from "Learn You A
Haskell For Great Good," but these are my own crappy examples.

This blog post is literate Haskell; you can get it
[here](https://gist.github.com/4145341). You can import it into ghci and type
the functions to see their output (`ghci monads.lhs`). For this to work, we'll
need to import one module for use later:

> import Control.Applicative

gatlin

{-# LANGUAGE DeriveFunctor #-}

import Control.Applicative
import Control.Comonad

import Control.Monad (forM_)

-- These two typeclasses probably make some people groan.
class LeftRight t where
    left :: t a -> t a

gatlin

Writing a billing system in Haskell, using Stripe and Heroku
===

*This post is written in literate Haskell, meaning the source can be turned
into a blogpost or a working program. You can view the [source][source].

[source]: https://gist.github.com/gatlin/7754289

Normally clients pay me with checks, but recently one informed me that they
really really really like *really really* super prefer some kind of online

gatlin

{-# LANGUAGE RankNTypes #-}

import Prelude hiding (IO, getLine)
import qualified Prelude as P
import System.IO.Unsafe

-- * The Foreign Function Interface

-- | FFI values permit interfacing with foreign functions, such as low-level IO
-- operations, memory management operations, or bindings to other user-level