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gatlin /
Created Oct 10, 2012
Uninstall Haskell from Mac OS X
# source:
sudo rm -rf /Library/Frameworks/GHC.framework
sudo rm -rf /Library/Frameworks/HaskellPlatform.framework
sudo rm -rf /Library/Haskell
rm -rf .cabal
rm -rf .ghc
rm -rf ~/Library/Haskell
gatlin / gist:d89ee5442c10ca59ac9a8b621392ed10
Created May 1, 2019
Oleg's CK machine macro system - ever so slightly easier to find cross device here
View gist:d89ee5442c10ca59ac9a8b621392ed10
; 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.
View free-compiler.hs
- Example of using free constructions to build a flexible little compiler.
- The goal here is not necessarily efficiency but readability and flexibility.
- The language grammar is represented by an ADT; however, instead of
- recursively referring to itself it instead references a type variable.
- We derive instances of 'Functor' and 'Traversable' for this type.
gatlin / monads.lhs
Created Nov 25, 2012
My explanation of monads
View monads.lhs
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]( 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 /
Last active Nov 25, 2018
A simple definition and demonstration of monads in Typed Racket

What the fuck is a monad?

Or: functor? I 'ardly know 'er!

Monads are difficult to explain without sounding either patronizing or condescending: I would sound patronizing if I came up with some facile analogy and I would be condescending to describe it categorically.

Instead, I'll frame a problem and piece-by-piece solve the problem with what will turn out to be a monad.

gatlin / yet-another-conway.hs
Last active Aug 20, 2018
Yet Another Comonadic Game of Life implementation in Haskell, in response to a Reddit thing. Much love to those who have done similar things previously. I'm really just a messenger here.
View yet-another-conway.hs
{-# 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 /
Last active Aug 13, 2018
Hask-- I mean, psilo with zero real typeclasses and one virtual typeclass
;; Hask-- I mean, psilo with no real typeclasses and one virtual typeclass.
; Inspired by [1], this is an exploration of representing all typeclasses
; through one distinguished class.
; This version of psilo does not have "real" typeclasses. However faking them
; with explicit dictionary passing does seem to correctly infer and check the
; constraints.
; The goal then is to figure out how best to represent "real" typeclasses as a
; distinguished feature in the language implementation given that we are
gatlin / sat.hs
Created Feb 6, 2012
SAT Solver in Haskell
View sat.hs
-- This is going to be on Hackage soon!
{-# LANGUAGE BangPatterns #-}
-- |
-- Module : AI.Surely
-- Copyright : 2012 Gatlin Johnson
-- License : LGPL 3.0
-- Maintainer :
-- Stability : experimental
View haskell-billing-server.lhs
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].
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
View io.hs
{-# 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
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