tester.hs

import Eval (eval)
results = [eval "(\\x. x) (\\x. x)" == "(\\ 0)",
           eval "(\\x. x x) (\\x. \\y. x)" == "(\\ (\\ (\\ 1)))",
           eval "(\\p. p (\\t. \\f. t)) ((\\f. \\s. \\b. b f s) (\\x. x) (\\x. \\y. x))" == "(\\ 0)",
           eval "(\\x. \\y. \\z. x z (y z)) (\\x. \\y. x) (\\x. \\y. x) (\\x. \\y. x)" == "(\\ (\\ 1))",
           eval "(\\m. m (\\x. \\t. \\f. f) (\\t. \\f. t)) ((\\n. \\s. \\z. s (n s z)) (\\s. \\z. s z))" == "(\\ (\\ 0))"]

main = do
    let xs = filter (not . snd) $ zip [0..] results :: [(Int, Bool)]
    if null xs then putStrLn "OK"
               else putStrLn $ "Failed in No." ++ (show $ fst $ head xs)