Re: [Haskell-cafe] Rotating backdrop (aka learning Haskell)

On Tue, 2008-05-20 at 10:55 +0200, Ketil Malde wrote:

Yann Golanski writes:

...

1- Get a list out of a file: I managed to do that using the following:

parseImageFile :: FilePath -> IO [String] parseImageFile file = do inpStr <- readFile file return $ filter (/="") (breaks (=='\n') inpStr)

Nice, simple and I understand what it is doing.

Can be improved:

breaks (=='\n') == lines -- easier to read, no? filter (/="") == filter (not . null) -- more polymorphic, not important here do x <- expr1 == expr1 >>= return . expr2 return $ expr2 x -- i.e. "readFile f >>= return . filter (not.null) . lines"

do x <- expr1; return $ expr2 x == expr1 >>= return . expr2 == liftM expr2 expr1 -- or fmap (a.k.a. <$>) if you like So, liftM (filter (not . null) . lines) readFile alternatively, filter (not . null) . lines <$> readFile