On Thu, Feb 4, 2010 at 12:29 PM, Casey Hawthorne
<caseyh@istar.ca> 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
>
From "Algorithms: a functional programming approach"
Second edition
Fethi Rabhi
Guy Lapalme
data Stack a = EmptyStk
| Stk a (Stack a)
push x s = Stk x s
pop EmptyStk = error "pop from an empty stack"
pop (Stk _ s) = s
top EmptyStk = error "top from an empty stack"
top (Stk x _) = x
emptyStack = EmptyStk
stackEmpty EmptyStk = True
stackEmpty _ = False
newtype Stack a = Stk [a]
push x (Stk xs) = Stk (x:xs)
pop (Stk []) = error "pop from an empty stack"
pop (Stk (_:xs)) = Stk xs
top (Stk []) = error "top from an empty stack"
top (Stk (x:_)) = x
emptyStack = Stk []
stackEmpty (Stk []) = True
stackEmpty (Stk _ ) = False
--
Regards,
Casey