Michael Fairley michaelfairley

Immutable Ruby

Most Ruby code makes heavy use of mutable state, which often contributes to long term maintenance problems. Mutability can lead to code that's difficult to understand, libraries and applications that aren't thread-safe, and tests that are slow and brittle. Immutability, on the other hand, can make code easy to reason about, safe to use in multi-threaded environments, and simple to test. Doesn't that sound nice?

This talk answers the question "why immutability?", covers the building blocks of immutable code, such as value objects and persistent data structures, as well as higher order concepts that make heavy use of immutability, such as event sourcing and pure functions, and finally discusses the tradeoffs involved in going immutable.

Michael Fairley

Michael Fairley is a developer at Braintree Payments, where he uses Ruby to make it easy for businesses around the world (including the UK!) to accept credit card payments online. He’s an active open source contributor, and maintains a han

jruby-go

Go's concurrency model on top of JRuby

Channels

Channel.new creates a channel, and you can optionally pass it a capacity: Channel.new(200)

Use << to send on a channel: chan << "stuff"

	#!/usr/bin/env python
	import mincemeat

	data = ["Humpty Dumpty sat on a wall",
	"Humpty Dumpty had a great fall",
	"All the King's horses and all the King's men",
	"Couldn't put Humpty together again",
	]

	def mapfn(k, v):

	a = nil \|\| 1
	puts a # prints 1

	b = nil or 1
	puts b # prints nil


	c = 1 && 2
	puts c # prints 2

	ruby-1.8.7-p330 :001 > 1 + 1
	=> 2
	ruby-1.8.7-p330 :002 > a = _
	=> 2
	ruby-1.8.7-p330 :003 > a
	=> 2

	require 'benchmark'
	require 'draper'

	class Model
	# 300 is about the fewest methods an ActiveRecord model will have
	300.times do \|i\|
	define_method :"method_#{i}" do
	i
	end
	end

	def memoize(&blk)
	cache = {}
	lambda do \|*args\|
	return cache[args] if cache.has_key?(args)
	cache[args] = blk.call(*args)
	end
	end

	define_singleton_method(:fib, &memoize{ \|n\|
	if n < 2

	source :rubygems

	gem 'activerecord', :require => 'active_record'

	the `path_param`/`auth` stuff seems ugly :-/
	How to convert response to json, etc. (ActiveModel Serializers?)
	Providers?
	Routing/registry