On Monday 23 July 2007, Alexteslin wrote:
Hi, first I like to thank all of you guys - it really helps!
I am still on a same chapter with higher order functions and this function is also confusing. But before i even define this function i am getting the type error - i don't know why? So i wrote the simpler one like:
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
To even my very little knowledge i think that this should work. What am i doing wrong?
You're passing only one argument to filterApha, when it takes two. Haskell can't figure out which arguments you want to stay the same on every recursive call, and which ones you want to vary, so you have to supply every argument every time. Jonathan Cast http://sourceforge.net/projects/fid-core http://sourceforge.net/projects/fid-emacs