Listen

eigentlich:

data List a = Nil {}
    | Cons { head :: a, tail :: List a }
aber aus historischen Gründen
data [a] = a : [a] | []
Pattern matching dafür:
length :: [a] -> Int
length l = case l of
    []     -> 0
    x : xs -> ...
Summe der Elemente einer Liste?



Johannes Waldmann 2010-01-25