jcdickinson

class IAmDisposable : IDisposable
{
    private int _isDisposed;
    private SomeDisposableThing _disposable1;
    private SomeDisposableBar _disposable2;
    private SomeDisposableBaz _disposable3;

    // Only if you **need** it. You don't though, use SafeHandle.
    //~IAmDisposable()
    //{

tonymorris

class Functor f => Extend f where
  -- CoSelectMany
  extend ::
    (f a -> b)
    -> f a
    -> f b

  -- CoFlatten?
  duplicate ::
    f a

sebfisch

Delimited Continuations

Delimited continuations manipulate the control flow of programs. Similar to control structures like conditionals or loops they allow to deviate from a sequential flow of control.

We use exception handling as another example for control flow manipulation and later show how to implement it using delimited continuations. Finally, we show that nondeterminism can also be expressed using delimited continuations.

Exception Handling

ry

var http = require('http')
var fork = require('child_process').fork;

function fib(n) {
  if (n < 2) {
    return 1;
  } else {
    return fib(n - 2) + fib(n - 1);
  }
}

ademar

// Based on the article 'Combinators for logic programming' by Michael Spivey and Silvija Seres.

let rec inf_seq n =  seq { yield n; yield! inf_seq (n+1) }

let rec lzw f l1 l2 =
    LazyList.delayed ( fun () -> 
    match l1,l2 with
    |LazyList.Nil, _ -> l2
    |_, LazyList.Nil -> l1
    |LazyList.Cons(p1,tail1),LazyList.Cons(p2,tail2)

ademar

// Learn more about F# at http://fsharp.net
open Microsoft.FSharp.Control
open System.Collections.Generic
open System.Threading
open System.IO

type RequestGate(n:int) = 
    let semaphore = new Semaphore(initialCount=n,maximumCount=n);
    member x.AcquireAsync(?timeout) = 
        async {

chriseidhof

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