Stdlib.Stack
Last-in first-out stacks.
This module implements stacks (LIFOs), with in-place modification.
Unsynchronized accesses
Unsynchronized accesses to a stack may lead to an invalid queue state. Thus, concurrent accesses to stacks must be synchronized (for instance with a Mutex.t
).
let create: unit => t('a);
Return a new stack, initially empty.
let push: 'a => t('a) => unit;
push x s
adds the element x
at the top of stack s
.
let pop: t('a) => 'a;
pop s
removes and returns the topmost element in stack s
, or raises Empty
if the stack is empty.
let pop_opt: t('a) => option('a);
pop_opt s
removes and returns the topmost element in stack s
, or returns None
if the stack is empty.
let drop: t('a) => unit;
drop s
removes the topmost element in stack s
, or raises Empty
if the stack is empty.
let top: t('a) => 'a;
top s
returns the topmost element in stack s
, or raises Empty
if the stack is empty.
let top_opt: t('a) => option('a);
top_opt s
returns the topmost element in stack s
, or None
if the stack is empty.
let clear: t('a) => unit;
Discard all elements from a stack.
let is_empty: t('a) => bool;
Return true
if the given stack is empty, false
otherwise.
let length: t('a) => int;
Return the number of elements in a stack. Time complexity O(1)
let iter: ('a => unit) => t('a) => 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.
let fold: ('acc => 'a => 'acc) => 'acc => t('a) => 'acc;
fold f accu s
is (f (... (f (f accu x1) x2) ...) xn)
where x1
is the top of the stack, x2
the second element, and xn
the bottom element. The stack is unchanged.
Iterate on the stack, top to bottom. It is safe to modify the stack during iteration.