mirror of
https://github.com/c-cube/ocaml-containers.git
synced 2025-12-09 12:45:34 -05:00
475 lines
11 KiB
OCaml
475 lines
11 KiB
OCaml
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(* This file is free software, part of containers. See file "license" for more details. *)
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type 'a iter = ('a -> unit) -> unit
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type 'a gen = unit -> 'a option
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type 'a equal = 'a -> 'a -> bool
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type 'a ord = 'a -> 'a -> int
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type 'a printer = Format.formatter -> 'a -> unit
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type + 'a t = unit -> 'a node
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and +'a node = 'a Seq.node =
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| Nil
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| Cons of 'a * 'a t
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let nil () = Nil
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let cons a b () = Cons (a,b)
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let empty = nil
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let singleton x () = Cons (x, nil)
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let rec _forever x () = Cons (x, _forever x)
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let rec _repeat n x () =
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if n<=0 then Nil else Cons (x, _repeat (n-1) x)
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let repeat ?n x = match n with
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| None -> _forever x
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| Some n -> _repeat n x
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let is_empty l = match l () with
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| Nil -> true
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| Cons _ -> false
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let head_exn l = match l() with | Nil -> raise Not_found | Cons (x, _) -> x
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let head l = match l() with Nil -> None | Cons (x, _) -> Some x
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let tail_exn l = match l() with | Nil -> raise Not_found | Cons (_, l) -> l
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let tail l = match l() with | Nil -> None | Cons (_, l) -> Some l
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let rec equal eq l1 l2 = match l1(), l2() with
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| Nil, Nil -> true
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| Nil, _
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| _, Nil -> false
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| Cons (x1,l1'), Cons (x2,l2') ->
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eq x1 x2 && equal eq l1' l2'
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let rec compare cmp l1 l2 = match l1(), l2() with
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| Nil, Nil -> 0
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| Nil, _ -> -1
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| _, Nil -> 1
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| Cons (x1,l1'), Cons (x2,l2') ->
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let c = cmp x1 x2 in
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if c = 0 then compare cmp l1' l2' else c
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let rec fold f acc res = match res () with
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| Nil -> acc
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| Cons (s, cont) -> fold f (f acc s) cont
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let fold_left = fold
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let rec iter f l = match l () with
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| Nil -> ()
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| Cons (x, l') -> f x; iter f l'
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let iteri f l =
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let rec aux f l i = match l() with
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| Nil -> ()
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| Cons (x, l') ->
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f i x;
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aux f l' (i+1)
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in
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aux f l 0
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let length l = fold (fun acc _ -> acc+1) 0 l
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let rec take n (l:'a t) () =
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if n=0 then Nil
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else match l () with
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| Nil -> Nil
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| Cons (x,l') -> Cons (x, take (n-1) l')
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let rec take_while p l () = match l () with
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| Nil -> Nil
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| Cons (x,l') ->
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if p x then Cons (x, take_while p l') else Nil
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let rec drop n (l:'a t) () = match l () with
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| l' when n=0 -> l'
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| Nil -> Nil
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| Cons (_,l') -> drop (n-1) l' ()
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let rec drop_while p l () = match l() with
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| Nil -> Nil
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| Cons (x,l') when p x -> drop_while p l' ()
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| Cons _ as res -> res
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let rec map f l () = match l () with
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| Nil -> Nil
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| Cons (x, l') -> Cons (f x, map f l')
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let mapi f l =
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let rec aux f l i () = match l() with
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| Nil -> Nil
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| Cons (x, tl) ->
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Cons (f i x, aux f tl (i+1))
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in
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aux f l 0
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let rec fmap f (l:'a t) () = match l() with
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| Nil -> Nil
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| Cons (x, l') ->
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begin match f x with
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| None -> fmap f l' ()
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| Some y -> Cons (y, fmap f l')
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end
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let rec filter p l () = match l () with
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| Nil -> Nil
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| Cons (x, l') ->
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if p x
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then Cons (x, filter p l')
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else filter p l' ()
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let rec append l1 l2 () = match l1 () with
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| Nil -> l2 ()
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| Cons (x, l1') -> Cons (x, append l1' l2)
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let rec cycle l () = append l (cycle l) ()
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let rec unfold f acc () = match f acc with
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| None -> Nil
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| Some (x, acc') -> Cons (x, unfold f acc')
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let rec for_all p l =
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match l () with
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| Nil -> true
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| Cons (x, tl) -> p x && for_all p tl
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let rec exists p l =
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match l () with
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| Nil -> false
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| Cons (x, tl) -> p x || exists p tl
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let rec flat_map f l () = match l () with
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| Nil -> Nil
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| Cons (x, l') ->
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_flat_map_app f (f x) l' ()
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and _flat_map_app f l l' () = match l () with
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| Nil -> flat_map f l' ()
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| Cons (x, tl) ->
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Cons (x, _flat_map_app f tl l')
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let product_with f l1 l2 =
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let rec _next_left h1 tl1 h2 tl2 () =
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match tl1() with
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| Nil -> _next_right ~die:true h1 tl1 h2 tl2 ()
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| Cons (x, tl1') ->
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_map_list_left x h2
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(_next_right ~die:false (x::h1) tl1' h2 tl2)
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()
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and _next_right ~die h1 tl1 h2 tl2 () =
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match tl2() with
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| Nil when die -> Nil
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| Nil -> _next_left h1 tl1 h2 tl2 ()
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| Cons (y, tl2') ->
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_map_list_right h1 y
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(_next_left h1 tl1 (y::h2) tl2')
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()
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and _map_list_left x l kont () = match l with
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| [] -> kont()
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| y::l' -> Cons (f x y, _map_list_left x l' kont)
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and _map_list_right l y kont () = match l with
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| [] -> kont()
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| x::l' -> Cons (f x y, _map_list_right l' y kont)
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in
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_next_left [] l1 [] l2
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let product l1 l2 =
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product_with (fun x y -> x,y) l1 l2
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let rec group eq l () = match l() with
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| Nil -> Nil
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| Cons (x, l') ->
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Cons (cons x (take_while (eq x) l'), group eq (drop_while (eq x) l'))
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let rec _uniq eq prev l () = match prev, l() with
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| _, Nil -> Nil
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| None, Cons (x, l') ->
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Cons (x, _uniq eq (Some x) l')
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| Some y, Cons (x, l') ->
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if eq x y
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then _uniq eq prev l' ()
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else Cons (x, _uniq eq (Some x) l')
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let uniq eq l = _uniq eq None l
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let rec filter_map f l () = match l() with
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| Nil -> Nil
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| Cons (x, l') ->
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begin match f x with
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| None -> filter_map f l' ()
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| Some y -> Cons (y, filter_map f l')
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end
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let flatten l = flat_map (fun x->x) l
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let range i j =
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let rec aux i j () =
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if i=j then Cons(i, nil)
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else if i<j then Cons (i, aux (i+1) j)
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else Cons (i, aux (i-1) j)
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in aux i j
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let (--) = range
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let (--^) i j =
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if i=j then empty
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else if i<j then range i (j-1)
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else range i (j+1)
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let rec fold2 f acc l1 l2 = match l1(), l2() with
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| Nil, _
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| _, Nil -> acc
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| Cons(x1,l1'), Cons(x2,l2') ->
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fold2 f (f acc x1 x2) l1' l2'
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let rec map2 f l1 l2 () = match l1(), l2() with
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| Nil, _
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| _, Nil -> Nil
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| Cons(x1,l1'), Cons(x2,l2') ->
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Cons (f x1 x2, map2 f l1' l2')
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let rec iter2 f l1 l2 = match l1(), l2() with
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| Nil, _
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| _, Nil -> ()
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| Cons(x1,l1'), Cons(x2,l2') ->
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f x1 x2; iter2 f l1' l2'
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let rec for_all2 f l1 l2 = match l1(), l2() with
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| Nil, _
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| _, Nil -> true
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| Cons(x1,l1'), Cons(x2,l2') ->
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f x1 x2 && for_all2 f l1' l2'
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let rec exists2 f l1 l2 = match l1(), l2() with
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| Nil, _
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| _, Nil -> false
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| Cons(x1,l1'), Cons(x2,l2') ->
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f x1 x2 || exists2 f l1' l2'
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let rec merge cmp l1 l2 () = match l1(), l2() with
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| Nil, tl2 -> tl2
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| tl1, Nil -> tl1
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| Cons(x1,l1'), Cons(x2,l2') ->
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if cmp x1 x2 < 0
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then Cons (x1, merge cmp l1' l2)
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else Cons (x2, merge cmp l1 l2')
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let rec zip a b () = match a(), b() with
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| Nil, _
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| _, Nil -> Nil
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| Cons (x, a'), Cons (y, b') -> Cons ((x,y), zip a' b')
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let unzip l =
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let rec first l () = match l() with
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| Nil -> Nil
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| Cons ((x,_), tl) -> Cons (x, first tl)
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and second l () = match l() with
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| Nil -> Nil
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| Cons ((_, y), tl) -> Cons (y, second tl)
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in
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first l, second l
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let zip_i seq =
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let rec loop i seq () = match seq() with
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| Nil -> Nil
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| Cons (x,tl) -> Cons ((i,x), loop (i+1) tl)
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in
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loop 0 seq
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(** {2 Implementations} *)
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let return x () = Cons (x, nil)
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let pure = return
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let (>>=) xs f = flat_map f xs
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let (>|=) xs f = map f xs
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let (<*>) fs xs = product_with (fun f x -> f x) fs xs
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(** {2 Conversions} *)
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let rec _to_rev_list acc l = match l() with
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| Nil -> acc
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| Cons (x,l') -> _to_rev_list (x::acc) l'
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let to_rev_list l = _to_rev_list [] l
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let to_list l =
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let rec direct i (l:'a t) = match l () with
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| Nil -> []
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| _ when i=0 -> List.rev (_to_rev_list [] l)
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| Cons (x, f) -> x :: direct (i-1) f
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in
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direct 200 l
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let of_list l =
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let rec aux l () = match l with
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| [] -> Nil
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| x::l' -> Cons (x, aux l')
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in aux l
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let of_array a =
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let rec aux a i () =
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if i=Array.length a then Nil
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else Cons (a.(i), aux a (i+1))
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in
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aux a 0
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let of_string s =
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let rec aux s i () =
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if i=String.length s then Nil
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else Cons (String.get s i, aux s (i+1))
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in
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aux s 0
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let to_array l =
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(* We contruct the length and list of seq elements (in reverse) in one pass *)
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let len = ref 0 in
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let ls = fold_left (fun acc x -> incr len; x :: acc) [] l in
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(* The length is used to initialize the array, and then to derive the index for
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each item, working back from the last. This lets us only traverse the list
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twice, instead of having to reverse it. *)
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match ls with
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| [] -> [||]
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| init::rest ->
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let a = Array.make !len init in
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(* Subtract 1 for len->index conversion and 1 for the removed [init] *)
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let idx = !len - 2 in
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ignore (List.fold_left (fun i x -> a.(i) <- x; i - 1) idx rest : int);
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a
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let rec to_iter res k = match res () with
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| Nil -> ()
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| Cons (s, f) -> k s; to_iter f k
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let to_gen l =
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let l = ref l in
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fun () ->
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match !l () with
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| Nil -> None
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| Cons (x,l') ->
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l := l';
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Some x
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type 'a of_gen_state =
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| Of_gen_thunk of 'a gen
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| Of_gen_saved of 'a node
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let of_gen g =
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let rec consume r () = match !r with
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| Of_gen_saved cons -> cons
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| Of_gen_thunk g ->
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begin match g() with
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| None ->
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r := Of_gen_saved Nil;
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Nil
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| Some x ->
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let tl = consume (ref (Of_gen_thunk g)) in
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let l = Cons (x, tl) in
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r := Of_gen_saved l;
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l
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end
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in
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consume (ref (Of_gen_thunk g))
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let sort ~cmp l =
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let l = to_list l in
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of_list (List.sort cmp l)
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let sort_uniq ~cmp l =
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let l = to_list l in
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uniq (fun x y -> cmp x y = 0) (of_list (List.sort cmp l))
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type 'a memoize =
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| MemoThunk
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| MemoSave of 'a node
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let rec memoize f =
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let r = ref MemoThunk in
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fun () -> match !r with
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| MemoSave l -> l
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| MemoThunk ->
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let l = match f() with
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| Nil -> Nil
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| Cons (x, tail) -> Cons (x, memoize tail)
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in
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r := MemoSave l;
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l
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(** {2 Fair Combinations} *)
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let rec interleave a b () = match a() with
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| Nil -> b ()
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| Cons (x, tail) -> Cons (x, interleave b tail)
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let rec fair_flat_map f a () = match a() with
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| Nil -> Nil
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| Cons (x, tail) ->
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let y = f x in
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interleave y (fair_flat_map f tail) ()
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let rec fair_app f a () = match f() with
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| Nil -> Nil
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| Cons (f1, fs) ->
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interleave (map f1 a) (fair_app fs a) ()
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let (>>-) a f = fair_flat_map f a
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let (<.>) f a = fair_app f a
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(** {2 Infix} *)
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module Infix = struct
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let (>>=) = (>>=)
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let (>|=) = (>|=)
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let (<*>) = (<*>)
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let (>>-) = (>>-)
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let (<.>) = (<.>)
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let (--) = (--)
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let (--^) = (--^)
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end
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(** {2 Monadic Operations} *)
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module type MONAD = sig
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type 'a t
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val return : 'a -> 'a t
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val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
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end
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module Traverse(M : MONAD) = struct
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open M
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let map_m f l =
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let rec aux acc l = match l () with
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| Nil -> return (of_list (List.rev acc))
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| Cons (x,l') ->
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f x >>= fun x' ->
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aux (x' :: acc) l'
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in
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aux [] l
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let sequence_m l = map_m (fun x->x) l
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let rec fold_m f acc l = match l() with
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| Nil -> return acc
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| Cons (x,l') ->
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f acc x >>= fun acc' -> fold_m f acc' l'
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end
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(** {2 IO} *)
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let pp ?(pp_start=fun _ () -> ()) ?(pp_stop=fun _ () -> ())
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?(pp_sep=fun out () -> Format.fprintf out ",@ ") pp_item fmt l =
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pp_start fmt ();
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let rec pp fmt l = match l() with
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| Nil -> ()
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| Cons (x,l') ->
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pp_sep fmt ();
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Format.pp_print_cut fmt ();
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pp_item fmt x;
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pp fmt l'
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in
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begin match l() with
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| Nil -> ()
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| Cons (x,l') -> pp_item fmt x; pp fmt l'
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end;
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pp_stop fmt ()
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