mirror of
https://github.com/c-cube/ocaml-containers.git
synced 2025-12-06 11:15:31 -05:00
372 lines
9.4 KiB
OCaml
372 lines
9.4 KiB
OCaml
(*
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Copyright (c) 2013, Simon Cruanes
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer. Redistributions in binary
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form must reproduce the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials provided with
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the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 Continuation List} *)
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type 'a sequence = ('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 = Buffer.t -> 'a -> unit
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type 'a formatter = Format.formatter -> 'a -> unit
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type + 'a t = unit ->
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[ `Nil
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| `Cons of 'a * 'a t
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]
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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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(*$T
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repeat ~n:4 0 |> to_list = [0;0;0;0]
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repeat ~n:0 1 |> to_list = []
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repeat 1 |> take 20 |> to_list = (repeat ~n:20 1 |> to_list)
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*)
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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 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 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 length l = fold (fun acc _ -> acc+1) 0 l
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let rec take n (l:'a t) () = match l () with
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| _ when n=0 -> `Nil
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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') when p x -> `Cons (x, take_while p l')
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| `Cons (_,l') -> take_while p l' ()
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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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(*$Q
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(Q.pair (Q.list Q.small_int) Q.small_int) (fun (l,n) -> \
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let s = of_list l in let s1, s2 = take n s, drop n s in \
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append s1 s2 |> to_list = l )
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*)
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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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(*$T
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(map ((+) 1) (1 -- 5) |> to_list) = (2 -- 6 |> to_list)
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*)
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let rec fmap f (l:'a t) () = match l() with
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| `Nil -> `Nil
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| `Cons (x, l') ->
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begin match f x with
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| None -> fmap f l' ()
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| Some y -> `Cons (y, fmap f l')
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end
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(*$T
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fmap (fun x -> if x mod 2=0 then Some (x*3) else None) (1--10) |> to_list \
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= [6;12;18;24;30]
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*)
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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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(*$T
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cycle (of_list [1;2]) |> take 5 |> to_list = [1;2;1;2;1]
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*)
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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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(*$T
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range 0 5 |> to_list = [0;1;2;3;4;5]
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range 0 0 |> to_list = [0]
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range 5 2 |> to_list = [5;4;3;2]
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*)
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let (--) = range
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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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(** {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 rec to_seq res k = match res () with
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| `Nil -> ()
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| `Cons (s, f) -> k s; to_seq 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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let sort ?(cmp=Pervasives.compare) 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=Pervasives.compare) 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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(** {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 ?(sep=",") pp_item buf l =
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let rec pp buf l = match l() with
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| `Nil -> ()
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| `Cons (x,l') -> Buffer.add_string buf sep; pp_item buf x; pp buf l'
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in
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match l() with
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| `Nil -> ()
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| `Cons (x,l') -> pp_item buf x; pp buf l'
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let print ?(sep=",") pp_item fmt l =
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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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Format.pp_print_string fmt sep;
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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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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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