I am stuck on an exercise in a haskell book (the craft of functional programming) chapter 7 exercise 7.18 I have to write a function to check does one list occur as a subsequence of another, i am having real difficulty trying to do this. I have a method which will tell me if one character occurs in the list but it won't work for a list of characters. the function should look like isSubsequence :: [chars] -> [chars] -> boolean
Try writing a list or string equality function first? That may help.
Thanks for getting back to me, have written this so far find :: [Char] -> Char -> Bool find [] n = False find (x:xs) n | x == n = True | otherwise = find xs x this will work to find if one character appears in a list but i dont understand how to call this recursively to find if a list occurs within a list. I have tried writing another function to call this but it won't work. Does anyone have a solution? thanks again Peter Stranney __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com