Clojure Syntax

Not many languages are simple enough to have their entire syntax conveniently summarized in a table that fits on one screen. Luckily, Clojure is. The following is a summary put together based on the Clojure reader documentation. I'm a fan of tabular data, so I put this together for my own personal reference.

Reader forms
Symbols	atom, foo-bar, *foo*, etc.
Literals	42, "foo", nil, true, false, \c, :foo
Keywords	:foo (like symbols, prefixed with colon)
Lists	(a b c)
Vectors	[a b c]
Maps (hashes)	{:a 1 :b 2} or {:a 1, :b 2}
Sets	#{:a :b :c}
Macro Characters
Quote	'form
Character	\a \b \c
Comment	; txt
Meta	^a ^b ^c
Deref	@form
Syntax-quote	` (backtick)
Unquote	~ (tilde)
Unquote-splicing	~@ (tilde at)
Macro Characters (Dispatch)
Sets	#{:a :b :c}
Regexp	#"pattern"
Metadata	#^{:a 1 :b 2} [1 2 3] or #^Type x
Var-quote	#'x
Anonymous function	#(fn [args] (...))
Ignore next form	#_

Crushing PNGs With Ruby

Nothing too special here... just a quick hack. I needed to recursively run pngcrush over a directory structure, and I couldn't find any examples of how to do this online. The following solves the problem nicely. Hopefully someone else finds this helpful.

#!/usr/bin/ruby

require 'fileutils'
require 'find'

input_dir = ARGV[0]
rewrite_dir = "/tmp/crush/"

raise("Usage #{$0} dirname") unless input_dir
Dir.mkdir(rewrite_dir) unless test(?d, rewrite_dir)

Find.find(input_dir) do |file|
  if file =~ /\.png$/
    base_dir = File.dirname(file)
    base_file = File.basename(file)
    new_dir = rewrite_dir + base_dir
    FileUtils.mkdir_p(new_dir) unless test(?d, new_dir)
    puts(%Q!pngcrush -reduce -brute "#{file}" "#{new_dir}/#{base_file}"!)
  end
end

From there, you can just do something like: crush.rb images | sh.