This module implements stacks (LIFOs), with in-place modification.

type 'a t

The type of stacks containing elements of type 'a.

exception Empty

Raised when pop is applied to an empty stack.

val create: unit -> 'a t

Return a new stack, initially empty.

val push: 'a -> 'a t -> unit

push x s adds the element x at the top of stack s.

val pop: 'a t -> 'a

pop s removes and returns the topmost element in stack s, or raises Empty if the stack is empty.

val top: 'a t -> 'a

top s returns the topmost element in stack s, or raises Empty if the stack is empty.

val clear : 'a t -> unit

Discard all elements from a stack.

val length: 'a t -> int

Return the number of elements in a stack.

val iter: f:('a -> unit) -> 'a t -> unit

iter f s applies f in turn to all elements of s, from the element at the top of the stack to the element at the bottom of the stack. The stack itself is unchanged.