Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/tests/conformance98/fullylazy/lazy2.hs
main = do mapM print (map func ['a'..'z']) func n = nfib 20 nfib 0 = 1 nfib 1 = 1 nfib x = nfib (x-1) + nfib (x-2)