dl.rb

#!/usr/bin/env ruby

percent = (ENV["D"] || "50").to_i
content = ARGF.read
if STDOUT.tty?
  print content.chars.map{|c| next c unless c.match(/[\x20-\x7f]/); rand(1..100) <= percent ? " " : c}.join
else
  print content
end

fib.rb

def fib(a)
  return a if a <= 1
  fib(a - 2) + fib(a - 1) 
end

puts fib(10)

usage.md

$ ./dl.rb ./fib.rb
 e    b( )
  ret    a  f   <=
  fib(a - 2) + fib(a - 1)
e d

p  s    (  )
$ D=50 ./dl.rb ./fib.rb
  f fi (a)
      r  a  f   <=
    b(    2    f b a   1
 n

puts   b   )
$ D=100 ./dl.rb ./fib.rb








$ ./dl.rb ./fib.rb | ruby
55
$ ./dl.rb ./fib.rb | ./dl.rb | ruby
55