[Haskell-cafe] ghci command line execution

A while ago I remember someone showing me some tool, I *think* ghci that allowed you to pass it a function of type String -> String as an input, and have it simply run that function on stdin (presumably using interact) to achieve useful things like this... $ cat myFile.txt | ghci -e 'unlines . zipWith (\x y -> show x ++ " " ++ y) [1..] . lines' Does anyone know what it was that I saw being used here? Thanks Tom Davie