Script to run against stdin if no arg; otherwise input file =ARGV[0]

Question

This works quite nicely - just wondered if there are any improvements to shorten it ?

if (ARGV[0].nil?) then
    input=$<
else
    input=File.new(ARGV[0],         


        

Answer 1

then and ; are optional

also you can use the ternary operator:

input = ARGV[0].nil? ? $< : File.new(ARGV[0],"r")