Maybe I should take a look at awk/sed but I never found its language orthogonal. For simple scripts I mostly use Python or Haskell via something like

ghc -e 'interact ((++"\n") . show . length . lines)' < file

EDIT:

I know that it's the same like "wc -l" but using that approach I can solve also problems that may not be well suited for awk/sed. Or maybe I just have to see some convincing one-liners.