Skip to content

Instantly share code, notes, and snippets.

@chpatrick
chpatrick / marshal.hs
Last active August 29, 2015 13:57
Automatic type-safe binding generation sketch (GHC HEAD)
{-# LANGUAGE TypeFamilies, GADTs, DataKinds, TypeOperators, FlexibleInstances, OverlappingInstances, ConstraintKinds, MultiParamTypeClasses, ForeignFunctionInterface #-}
import Control.Applicative
import Foreign
import Foreign.C
-- heterogenous list
data HList (ts :: [ * ]) where
E :: HList '[]
(:.) :: t -> HList ts -> HList (t ': ts)

Hi, looking for scalac flags?

This gist has been upgraded to a blog post here.

@rothgar
rothgar / main.yml
Last active April 28, 2025 04:18
Generate /etc/hosts with Ansible
# Idempotent way to build a /etc/hosts file with Ansible using your Ansible hosts inventory for a source.
# Will include all hosts the playbook is run on.
# Inspired from http://xmeblog.blogspot.com/2013/06/ansible-dynamicaly-update-etchosts.html
- name: "Build hosts file"
lineinfile: dest=/etc/hosts regexp='.*{{ item }}$' line="{{ hostvars[item].ansible_default_ipv4.address }} {{item}}" state=present
when: hostvars[item].ansible_default_ipv4.address is defined
with_items: groups['all']
@bitemyapp
bitemyapp / gist:8739525
Last active May 7, 2021 23:22
Learning Haskell
@tonymorris
tonymorris / scalaz.scala
Created January 5, 2014 01:16
Questions about \/ and Validation
// Questions about \/ and Validation
object scalaz {
/*
This explanation might help. This is a compilable source file with revisions
available at https://gist.github.com/tonymorris/8263051
Fact: All monads are applicative functors. As has been seen we can witness the
`Applicative` that arises from the `Monad` primitives. Let's illustrate this:
@debasishg
debasishg / gist:8172796
Last active August 28, 2025 14:19
A collection of links for streaming algorithms and data structures

General Background and Overview

  1. Probabilistic Data Structures for Web Analytics and Data Mining : A great overview of the space of probabilistic data structures and how they are used in approximation algorithm implementation.
  2. Models and Issues in Data Stream Systems
  3. Philippe Flajolet’s contribution to streaming algorithms : A presentation by Jérémie Lumbroso that visits some of the hostorical perspectives and how it all began with Flajolet
  4. Approximate Frequency Counts over Data Streams by Gurmeet Singh Manku & Rajeev Motwani : One of the early papers on the subject.
  5. [Methods for Finding Frequent Items in Data Streams](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.9800&rep=rep1&t
@pchiusano
pchiusano / queues.markdown
Created December 22, 2013 19:43
Binding to asynchronous processes using scalaz-stream

When creating streams from an asynchronous process, the idiomatic thing is to create a stream from that process at the earliest possible stage, rather than using a queue to invert control after the fact. See the creating streams examples - generally, you just use the Process.eval and Process.repeatEval functions to build a stream by running some asynchronous task repeatedly.

That said, if you have some existing logic that you need to bind to that's already based on callbacks and side effects, you can use the functions in scalaz.stream.async. Here's an example, using a queue to invert control:

import scalaz.stream.async

val (q, src) = async.queue[Int]

// Thread 1
@ptomato
ptomato / debug.js
Created November 18, 2013 05:39
GJS debugger
const GLib = imports.gi.GLib;
const Lang = imports.lang;
const System = imports.system;
let _breakpoints = 0;
function _getCurrentStack() {
try {
throw new Error();
} catch (e) {
@mzero
mzero / ghc-clang-wrapper
Created October 31, 2013 06:53
This wrapper script *should* enable GHC 7.* to work on systems with Xcode 5. To use it, drop this script somewhere, make it executable, and run.... Then follow the instructions it prints out. What it will do is, instruction you to put a copy in /usr/bin, then re-run it sudo. It will then find all your GHC 7 settings files, and patch them to make…
#!/bin/sh
inPreprocessorMode () {
hasE=0
hasU=0
hasT=0
for arg in "$@"
do
if [ 'x-E' = "x$arg" ]; then hasE=1; fi
if [ 'x-undef' = "x$arg" ]; then hasU=1; fi
anonymous
anonymous / Haskell
Created October 7, 2013 19:22
Comparison of the straightforward embedding of a basic tenet of category theory in Scala vs Haskell.
yonedaLemma = Iso (flip fmap) ($ id)