On Feb 5, 2010, at 6:38 AM, Casey Hawthorne wrote:
On Thu, 4 Feb 2010 09:07:28 -0800 (PST), you wrote:
Can't find a Stack datatype on Hoogle? Where should I look?
Michael
module Stack(Stack,push,pop,top,emptyStack,stackEmpty) where
...
Or just use a list.
A more Haskellish approach to stacks than using "pop" and "top"
would be something like this:
newtype Stack t = [t]
emptyStack = Stack []
stackPush (Stack s) = Stack (x:s)
viewStack (Stack []) = Nothing
viewStack (Stack (top:rest)) = Just (top, Stack rest)
Instead of
if stackEmpty s then ... else ... top s ... pop s ...
do
case viewStack s of
Nothing -> ...
Just (top, rest) -> ...
Note that none of the functions in this interface can fail.
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