At 10:50 AM +0900 2005/4/16, Kaoru Hosokawa wrote:
My solution based on Bernie's solution:
init :: [a] -> [a] init xs = foldr (left (length xs)) xs xs
left :: Int -> a -> [a] -> [a] left n x xs | n == length xs = [] | otherwise = x : xs
I use the foldr return value for the empty list as the input itself. Use this value as a marker to signify that I am at the end of the list by checking its length.
Using length causes this definition of init to fail on infinite lists. --Ham -- ------------------------------------------------------------------ Hamilton Richards, PhD Department of Computer Sciences Senior Lecturer The University of Texas at Austin 512-471-9525 1 University Station C0500 Taylor Hall 5.138 Austin, Texas 78712-0233 ham@cs.utexas.edu hrichrds@swbell.net http://www.cs.utexas.edu/users/ham/richards ------------------------------------------------------------------