úÎ#™!½!      SafeAbstract Stack data typeO(1). Create new empty StackO(1). Push item onto Stack 0("x)("s)(stackPop (stackPush s x) == Just (s,x))O(1)>. Pop most recently added item without removing from the Stack vstackPeek stackNew == Nothing ("x)("s)(stackPeek (stackPush s x) == Just x) ("s)(stackPeek s == fmap snd (stackPop s))O(1)). Pop most recently added item from Stack MstackPop stackNew == Nothing ("x)("s)(stackPop (stackPush s x) == Just (s,x))O(1). Test if stack is empty €stackIsEmpty stackNew == True ("x)("s)(stackIsEmpty (stackPush s x) == True) ("s)((stackSize s == 0) !Ô (stackIsEmpty s == True))O(1)3. Compute number of elements contained in the Stack YstackSize stackNew == 0 ("x)("s)((stackSize s == n) !Ò (stackSize (stackPush s x) == n+1))!!Safe >A mutable stack in state thread s, containing values of type a Create new empty Stack Push item onto Stack <Pop most recently added item without removing from the Stack 'Pop most recently added item from StackTest if stack is empty1Compute number of elements contained in the Stack "    " Safe Synchronized stack data typeCreate new empty StackPush item onto Stack<Pop most recently added item without removing from the Stack<Pop most recently added item without removing from the Stack'Automatically retries if stack is empty'Pop most recently added item from Stack'Pop most recently added item from Stack'Automatically retries if stack is emptyTest if stack is empty1Compute number of elements contained in the Stack #   #SafeCreate new empty StackPush item onto Stack<Pop most recently added item without removing from the Stack<Pop most recently added item without removing from the StackBlocks if stack is empty'Pop most recently added item from Stack'Pop most recently added item from StackBlocks if stack is emptyTest if stack is empty 1Compute number of elements contained in the Stack    $              "Stack-0.3.2-DA5ThcxubVw6ORhJF4yGaN Data.Stack Data.Stack.STControl.Concurrent.STM.StackControl.Concurrent.StackStackstackNew stackPush stackPeekstackPop stackIsEmpty stackSize $fReadStack $fShowStack stackTryPeek stackTryPop