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|
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012 *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
type 'a t =
| Nil
| Cons of 'a * 'a t
| Lazy of 'a t Lazy.t
let empty = Nil
let cons x s = Cons (x, s)
let thunk s = Lazy s
let rec force = function
| Nil -> ()
| Cons (_, s) -> force s
| Lazy t -> force (Lazy.force t)
let force s = force s; s
let rec is_empty = function
| Nil -> true
| Cons (_, _) -> false
| Lazy t -> is_empty (Lazy.force t)
let rec peek = function
| Nil -> None
| Cons (x, s) -> Some (x, s)
| Lazy t -> peek (Lazy.force t)
let rec of_list = function
| [] -> Nil
| x :: l -> Cons (x, of_list l)
let rec to_list = function
| Nil -> []
| Cons (x, s) -> x :: (to_list s)
| Lazy t -> to_list (Lazy.force t)
let rec iter f = function
| Nil -> ()
| Cons (x, s) -> f x; iter f s
| Lazy t -> iter f (Lazy.force t)
let rec map f = function
| Nil -> Nil
| Cons (x, s) -> Cons (f x, map f s)
| Lazy t -> Lazy (lazy (map f (Lazy.force t)))
let rec app s1 s2 = match s1 with
| Nil -> s2
| Cons (x, s1) -> Cons (x, app s1 s2)
| Lazy t ->
let t = lazy (app (Lazy.force t) s2) in
Lazy t
let rec fold f accu = function
| Nil -> accu
| Cons (x, s) -> fold f (f accu x) s
| Lazy t -> fold f accu (Lazy.force t)
let rec map_filter f = function
| Nil -> Nil
| Cons (x, s) ->
begin match f x with
| None -> map_filter f s
| Some y -> Cons (y, map_filter f s)
end
| Lazy t ->
let t = lazy (map_filter f (Lazy.force t)) in
Lazy t
let rec concat = function
| Nil -> Nil
| Cons (s, sl) -> app s (concat sl)
| Lazy t ->
let t = lazy (concat (Lazy.force t)) in
Lazy t
let lempty = Lazy (lazy Nil)
|
