Silly scripting language golf. Must read in a line of input, take out all of the spaces, and print it _immediately_ (so it can be sort of interactive).

line_joiner.hs

#!/usr/bin/env runhaskell

import Data.List (intercalate)

joinLines input = unlines $ map joinLine (lines input)
    where
        joinLine line = intercalate "" (words line)

main = interact joinLines

line_joiner.pl

#!/usr/bin/perl
s/ //g xor print while <>;

line_joiner.py

#!/usr/bin/env python

try: 
    while True:
        print(''.join(raw_input().split()))
except EOFError:
    pass