Stack by array

stack.ml

let lmax = 100

type 'a stack = { tab: 'a array; mutable length: int }

let empty default =
    { tab = Array.make lmax default; length = 0 }

let push x stack = match stack with
    | { tab = _; length = 100 } -> failwith "Stack overflow"
    | { tab = t; length = n } -> t.(n + 1) <- x; stack.length <- n + 1

let pop stack = match stack with
    | { tab = _; length = 0 } -> failwith "Stack underflow" (* lol *)
    | { tab = t; length = n } -> stack.length <- n - 1; t.(n)