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58 lines
1.2 KiB
58 lines
1.2 KiB
5 years ago
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(*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*)
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module type S = sig
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type 'a t
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val return : 'a -> 'a t
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val bind : ('a -> 'b t) -> 'a t -> 'b t
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module Import : sig
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val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
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val ( >>| ) : 'a t -> ('a -> 'b) -> 'b t
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val ( let* ) : 'a t -> ('a -> 'b t) -> 'b t
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val ( and* ) : 'a t -> 'b t -> ('a * 'b) t
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val ( let+ ) : 'a t -> ('a -> 'b) -> 'b t
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val ( and+ ) : 'a t -> 'b t -> ('a * 'b) t
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end
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end
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module State (State : sig
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type t
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end) =
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struct
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type state = State.t
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type 'a t = state -> 'a * state
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let return a s = (a, s)
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let bind k m s =
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let a, s = m s in
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k a s
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let run m s = m s
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module Import = struct
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let ( >>= ) m k = bind k m
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let ( let* ) m k = bind k m
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let ( and* ) : 'a t -> 'b t -> ('a * 'b) t =
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fun m n s ->
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let a, s = m s in
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let b, s = n s in
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return (a, b) s
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let ( >>| ) : 'a t -> ('a -> 'b) -> 'b t =
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fun m f ->
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let* a = m in
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return (f a)
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let ( let+ ) = ( >>| )
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let ( and+ ) = ( and* )
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end
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end
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