From ad1b2ed1e8fb4ec549318a27b5f80d2a6651b2dd Mon Sep 17 00:00:00 2001 From: Jed Barber Date: Thu, 27 Sep 2012 18:50:16 +1000 Subject: Stack datatype now deriving Eq --- Library/Stack.hs | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/Library/Stack.hs b/Library/Stack.hs index 7292869..29dd17c 100644 --- a/Library/Stack.hs +++ b/Library/Stack.hs @@ -3,14 +3,15 @@ module Library.Stack ( empty, at, pop, - (<:>) + (<:>), + size ) where import Data.List -data Stack a = Stack [a] +data Stack a = Stack [a] deriving (Eq) instance Show a => Show (Stack a) where @@ -37,3 +38,7 @@ pop n (Stack list) = Stack (drop n list) (<:>) :: a -> Stack a -> Stack a x <:> (Stack list) = Stack (x : list) + + +size :: Stack a -> Int +size (Stack list) = length list -- cgit