markhibberd markhibberd

Installation

FreeBSD

portmaster irc/irssi
portmaster irc/irssi-xmpp

OS X

brew install irssi

A course aimed at learning Scala. Rather than a traditional set of canned exercises, we will spend approx 12 weeks (more or less as required) building a complete system, and a system that may even be useful. The exercise is still contrived, in that we will attempt to implement far more of the code by hand than would normally occur, but we will build a series of components that are likely to be similar to code produced in a production setting.

The proposed exercise is to build a source code search engine on top of the venerable Ctags index format. This will involve

Chef Cheat sheet

Configuring Chef

To install stuff needed to run chef in a solo mode (Small one or two server configuration):

gem install knife-solo

To setup chef after it has been installed:

Overview

There are lots of representations for strings. In most languages they pick one set of tradeoffs and run with it. In haskell the "default" implementation (at least the one in the prelude) is a pretty bad choice, but unlike most other languages (really) good implementations exist for pretty much every way you can twist these things. This can be a good thing, but it also leads to confusion, and frustration to find the right types and how to convert them.

	Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_37).
	Type in expressions to have them evaluated.
	Type :help for more information.

	scala> import scalaz.std.string._
	import scalaz.std.string._

	scala> import scalaz.syntax.validation._
	import scalaz.syntax.validation._

	object IsEmpty

	class Holder[A, B](private var value: A) {
	def set(a: A)(implicit ev: B =:= IsEmpty.type) {
	value = a
	}
	}

	object Holder {
	def empty[A]: Holder[A, IsEmpty.type] =

	scala> implicit def x: String = "asgasgf"
	x: String

	scala> def foo(a: Int)(implicit x: Int, y: String = implicitly[String]): String = "a"
	foo: (a: Int)(implicit x: Int, implicit y: String)String

	scala> foo(1)(2)
	res2: String = a

	case class Utf8String(value: String)

	object Utf8String {
	implicit val ArbitraryUtf8String: Arbitrary[Utf8String] =
	Arbitrary(arbitrary[String] map (k =>
	Utf8String(k filter (c => c < '\ud800' \|\| c > '\udfff'))))
	}


	case class Blat[A](v: String \/ A) {
	def isValue =
	value.isDefined

	def isMessage =
	message.isDefined

	def value: Option[A] =
	v.toOption