(lispkit stack)

Library (lispkit stack) provides an implementation for mutable stacks, i.e. mutable LIFO buffers.

stack-type-tag

Symbol representing the stack type. The type-for procedure of library (lispkit type) returns this symbol for all stack objects.

(make-stack)

Returns a new empty stack.

(stack x ...)

Returns a new stack with x on its top position followed by the remaining parameters.

(stack-top (stack 1 2 3))  ⇒ 1 

(stack? obj)

Returns #t if obj is a stack; otherwise #f is returned.

(stack-empty? s)

Returns #t if stack s is empty.

(stack-size s)

Returns the size of stack s, i.e. the number of elements buffered in s.

(stack=? s1 s2)

Returns #t if stack s1 has the exact same elements in the same order like stack s2; otherwise, #f is returned.

(stack-push! s x)

Pushes element x onto stack s.

(stack-top s)

Returns the top element of stack s. If the stack is empty, an error is raised.

(stack-pop! s)

Removes the top element from stack s and returns its value.

(define s (make-stack))
(stack-push! s 1)
(stack-push! s 2)
(stack-pop! s)  ⇒ 2
(stack-size s)  ⇒ 1

(stack-clear! s)

Removes all elements from stack s.

(stack-copy s)

Returns a copy of stack s.

(stack->list s)

Returns a list consisting of all elements on stack s in the order they appear, i.e. starting with the top element.

(stack->list (stack 1 2 3))

(list->stack l)

Returns a new stack consisting of the elements of list l. The first element in l will become the top element of the stack that is returned.

(list->stack! s l)

Pushes the elements of list l onto stack s in reverse order.

(define s (list->stack '(3 2 1)))
(list->stack! s '(6 5 4))
(stack->list s)  ⇒ (6 5 4 3 2 1)