author | haftmann |
Tue, 18 Sep 2007 07:36:09 +0200 | |
changeset 24618 | 6ab574864cd4 |
parent 24421 | acfb2413faa3 |
child 24628 | 33137422d7fd |
permissions | -rw-r--r-- |
module Codegen where { import qualified Nat; class Null a where { nulla :: a; }; heada :: (Codegen.Null b) => [b] -> b; heada (x : xs) = x; heada [] = Codegen.nulla; instance Codegen.Null (Maybe b) where { nulla = Nothing; }; dummy :: Maybe Nat.Nat; dummy = Codegen.heada [Just (Nat.Suc Nat.Zero_nat), Nothing]; }