1 files changed, 57 insertions, 0 deletions
diff --git a/week3/mart/StdStack.icl b/week3/mart/StdStack.icl
new file mode 100644
index 0000000..13220e1
--- /dev/null
+++ b/week3/mart/StdStack.icl
@@ -0,0 +1,57 @@
+implementation module StdStack
+
+import StdEnv
+
+:: Stack a = Stack [a]
+
+newStack :: Stack a
+newStack = Stack []
+
+push     ::  a  (Stack a) -> Stack a
+push x (Stack xs) = Stack [x:xs]
+
+pushes   :: [a] (Stack a) -> Stack a
+pushes [] (Stack s) = Stack s
+pushes [x:xs] (Stack s) = pushes xs (push x (Stack s))
+
+pop      ::     (Stack a) -> Stack a
+pop (Stack []) = abort "Can't pop from empty stack..."
+pop (Stack [x:xs]) = Stack xs
+
+popn     :: Int (Stack a) -> Stack a
+popn 0 s = s
+popn n s = popn (n-1) (pop s)
+
+top      ::     (Stack a) -> a
+top (Stack []) = abort "Can't give top of empty stack..."
+top (Stack [x:_]) = x
+
+topn     :: Int (Stack a) -> [a]
+topn 0 _ = []
+topn n x = [top x:topn (n-1) (pop x)]
+
+elements ::     (Stack a) -> [a]
+elements (Stack s) = s
+
+count    ::     (Stack a) -> Int
+count (Stack []) = 0
+count (Stack [_:xs]) = 1 + count (Stack xs)
+
+Start  = ( "s0 = newStack = ",        s0,'\n'
+         , "s1 = push 1 s0 = ",       s1,'\n'
+         , "s2 = pushes [2..5] s1 = ",s2,'\n'
+         , "s3 = pop s2 = ",          s3,'\n'
+         , "s4 = popn 3 s3 = ",       s4,'\n'
+         , "s5 = top s4 = ",          s5,'\n'
+         , "s6 = topn 3 s2 = ",       s6,'\n'
+         , "s7 = elements s2 = ",     s7,'\n'
+         )
+where
+	s0 = newStack
+	s1 = push 1 s0
+	s2 = pushes [2..5] s1
+	s3 = pop s2
+	s4 = popn 3 s3
+	s5 = top s4
+	s6 = topn 3 s2
+	s7 = elements s2