Source file state_intf.ml

(* This file is part of 'travesty'.

   Copyright (c) 2018 by Matt Windsor

   Permission is hereby granted, free of charge, to any person
   obtaining a copy of this software and associated documentation
   files (the "Software"), to deal in the Software without
   restriction, including without limitation the rights to use, copy,
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   of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE. *)

open Core_kernel

(** [Generic] contains the signature bits common to all state monad
    signatures. *)
module type Generic = sig
  include State_transform_intf.Generic_builders
  (** State monads share the signatures of their builder functions with
      state transformers... *)

  include State_transform_intf.Generic_runners
    with type ('a, 's) t := ('a, 's) t
     and type 'a final := 'a final
     and type 's state := 's state
  (** ...as well as their runner functions... *)

  include State_transform_intf.Fix with type ('a, 's) t := ('a, 's) t
  (** ...and fixed-point combinators. *)
end

(** [S] is the signature of state monads parametrised over their
    value, but with a fixed state type. *)
module type S = sig
  type state
  (** The fixed state type. *)

  include Monad.S
  include T_monad.Extensions with type 'a t := 'a t
  include Generic with type ('a, 's) t := 'a t
                   and type 's state := state
                   and type 'a final := 'a
end

(** [S2] is the signature of state monads parametrised over both
    value and state types. *)
module type S2 = sig
  include Monad.S2
  include Generic with type ('a, 's) t := ('a, 's) t
                   and type 's state := 's
                   and type 'a final := 'a
end