wc -l in Ruby

wc.rb

#!/usr/bin/env ruby

# Example implementation of wc -l

(ARGV.length == 0 ?
 [["", STDIN]] :
 ARGV.lazy.map { |file_name|
	  [file_name, File.open(file_name)]
 })
.map { |file_name, file|
  "%8d %s\n" % [*file
                  .each_line
                  .lazy
                  .map { |line| 1 }
                  .reduce(:+), file_name]
}
.each(&:display)