apfelmus wrote:
Alexteslin wrote:
filterAlpha :: (a -> Bool) -> [a] -> [a] filterAlpha f [] = [] filterAlpha f (x:xs) |f x = x : filterAlpha xs |otherwise = filterAlpha xs
and i am getting this error message:
Type error in application Expression :filterAlpha xs Type : [b] Dous not match : a -> Bool
filterAlpha :: (a -> Bool) -> [a] -> [a] filterAlpha f [] = [] filterAlpha f (x:xs) | f x = x : filterAlpha f xs | otherwise = filterAlpha f xs
filterAlpha has two parameters. The first parameter is a function (a -> Bool), the second is a list [a]. The error message complains that xs , which you actidentially gave as first parameter, is a list [a] and not a function (a -> Bool).
Regards, apfelmus
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Oh silly me. I defined firstFirst now, thank you. -- View this message in context: http://www.nabble.com/filterFirst-tf4131377.html#a11751421 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.