(************************************************************
   lib_sequence.ml	Created      : Fri Feb 22 00:42:54 2002
  			Last modified: Wed Feb 27 23:46:34 2002
  Compile: make #
************************************************************)
exception Empty
open Lazy
type 'a delayed = 'a Lazy.status ref
type 'a seq = Nil | Sequence of ('a * ('a seq) delayed)

let head = function
    Sequence (a,_) -> (* 11916 *) a
  | _ -> (* 0 *) raise Empty
let tail = function
    Sequence (_,b) -> (* 11905 *) force b
  | _ -> (* 0 *) raise Empty
let nil = Nil
let is_empty = function
    Nil -> (* 0 *) true
  | _ -> (* 0 *) false
let cons a b = (* 12118 *) Sequence(a,b)
let rec take stream n = 
  (* 0 *) if n = 0 then (* 0 *) []
  else (* 0 *) match stream with
    Sequence (a,b) -> (* 0 *) a::(take (force b) (n-1))
  | _ -> (* 0 *) raise Empty
let rec nth n stream = 
  (* 200 *) if n = 0 then (* 2 *) head stream
  else 
    (* 198 *) nth (n-1) (tail stream)