doc-src/Codegen/Thy/examples/Example.hs
author blanchet
Thu, 24 Mar 2011 17:56:59 +0100
changeset 42108 f55562e77d5c
parent 41185 d5f0e556ffd3
child 44970 52f809bc5402
permissions -rw-r--r--
add "-?" to "nitrox" tool

{-# LANGUAGE ScopedTypeVariables #-}

module Example where {

data Queue a = AQueue [a] [a];

empty :: forall a. Queue a;
empty = AQueue [] [];

dequeue :: forall a. Queue a -> (Maybe a, Queue a);
dequeue (AQueue [] []) = (Nothing, AQueue [] []);
dequeue (AQueue xs (y : ys)) = (Just y, AQueue xs ys);
dequeue (AQueue (v : va) []) =
  let {
    (y : ys) = reverse (v : va);
  } in (Just y, AQueue [] ys);

enqueue :: forall a. a -> Queue a -> Queue a;
enqueue x (AQueue xs ys) = AQueue (x : xs) ys;

}