続編 - RubyにHaskellよりも強力なパターンマッチを実装した ref: http://qiita.com/egisatoshi/items/dfa13e45edbc71430048

file0.txt

require 'egison'
require 'prime'

include Egison

twin_primes = match_stream(Prime) {
  with(List.(*_, _x, __("x + 2"), *_)) {
    [x, x + 2]
  }
}

# print the first 10 prime twins
p twin_primes.take(10)
#=>[[3, 5], [5, 7], [11, 13], [17, 19], [29, 31], [41, 43], [59, 61], [71, 73], [101, 103], [107, 109]]