Am Mittwoch 09 Dezember 2009 01:59:21 schrieb zaxis:
findHelper (x:xs) = do -- not lazy, but that's not really important here filex <- fileExists (file x) filex' <- fileExists (file' x) case () of _
| filex -> return $ Just $ file x | filex' -> return $ Just $ file' x | otherwise -> findHelper xs
Such a 'case' is a typographically more pleasant way to test multiple alternatives than a nested if-then-else chain. With an if-then-else chain, the code would wander to the right and be less easily followed. Using a case () of _ | condition1 -> thing1 | condition2 -> thing2 | condition3 -> thing3 ... you can nicely align all possibilities. Since the 'case' here is extraneous to the code logic and serves only aesthetic ends, such a practice may be frowned upon.
file x = foldl1 joinFileName (x ++ [helper]) file' x = (file x) ++ (getConfig "exe_ext")
Sincerely!