Am 02.01.2012 10:44, schrieb max:
I want to write a function whose behavior is as follows:
foo "string1\nstring2\r\nstring3\nstring4" = ["string1",
"string2\r\nstring3", "string4"]
Note the sequence "\r\n", which is ignored. How can I do this?
replace the sequence by something unique first, i.e. a single "\r" (and
revert this change later).
(Replacing a single character is easier using concatMap).
HTH Christian
-- | replace first (non-empty) sublist with second one in third
-- argument list
replace :: Eq a => [a] -> [a] -> [a] -> [a]
replace sl r = case sl of
[] -> error "replace: empty list"
_ -> concat . unfoldr (\ l -> case l of
[] -> Nothing
hd : tl -> Just $ case stripPrefix sl l of
Nothing -> ([hd], tl)
Just rt -> (r, rt))
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