Functorize ocamlformat-rpc-lib over the IO (ocaml-ppx#1975)

Author: Guillaume Petiot

CHANGES.md

@@ -16,6 +16,11 @@
 
 #### New features
 
+#### RPC
+
+  + ocamlformat-rpc-lib is now functorized over the IO (#1975, @gpetiot).
+    Now handles `Csexp.t` types instead of `Sexplib0.Sexp.t`.
+
 ### 0.20.1 (2021-12-13)
 
 #### New features

bin/ocamlformat-rpc/main.ml

@@ -18,6 +18,28 @@ Caml.at_exit (Format.pp_print_flush Format.err_formatter);;
 
 Caml.at_exit (Format_.pp_print_flush Format_.err_formatter)
 
+module IO = struct
+  type 'a t = 'a
+
+  type ic = In_channel.t
+
+  type oc = Out_channel.t
+
+  let ( >>= ) x f = f x
+
+  let return x = x
+
+  let read ic =
+    match Csexp.input ic with
+    | Ok x -> return (Some x)
+    | Error _ -> return None
+
+  let write oc lx =
+    List.iter lx ~f:(Csexp.to_channel oc) ;
+    Out_channel.flush oc ;
+    return ()
+end
+
 module V = struct
   type t = V1
 
@@ -30,6 +52,8 @@ end
 
 type state = Waiting_for_version | Version_defined of (V.t * Conf.t)
 
+include Make (IO)
+
 let format fg conf source =
   let input_name = "<rpc input>" in
   let opts = Conf.{debug= false; margin_check= false} in
@@ -145,7 +169,9 @@ let info =
         "Once the client and the server agree on a common version, the \
          requests you can send may differ from one version to another."
     ; `P "On version $(b,v1), the supported RPC commands are:"
-    ; `P "- $(b,Halt) to close the connection to the RPC"
+    ; `P
+        "- $(b,Halt) to end the communication with the RPC server. The \
+         caller must close the input and output channels."
     ; `P
         "- $(b,Config) $(i,CSEXP): submits a list of (key, value) pairs (as \
          a canonical s-expression) to update OCamlFormat's configuration \

dune-project

@@ -161,5 +161,4 @@
    (and
     (>= 4.08)
     (< 4.15)))
-  csexp
-  sexplib0))
+  csexp))

lib-rpc/IO.ml

@@ -0,0 +1,35 @@
+(**************************************************************************)
+(*                                                                        *)
+(*                              OCamlFormat                               *)
+(*                                                                        *)
+(*            Copyright (c) Facebook, Inc. and its affiliates.            *)
+(*                                                                        *)
+(*      This source code is licensed under the MIT license found in       *)
+(*      the LICENSE file in the root directory of this source tree.       *)
+(*                                                                        *)
+(**************************************************************************)
+
+(** The [IO] module defines the blocking interface for reading and writing to
+    Cohttp streams *)
+
+module type S = sig
+  (** ['a t] represents a blocking monad state *)
+  type +'a t
+
+  val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
+  (** [a >>= b] will pass the result of [a] to the [b] function. This is a
+      monadic [bind]. *)
+
+  val return : 'a -> 'a t
+  (** [return a] will construct a constant IO value. *)
+
+  (** [ic] represents an input channel *)
+  type ic
+
+  (** [oc] represents an output channel *)
+  type oc
+
+  val read : ic -> Csexp.t option t
+
+  val write : oc -> Csexp.t list -> unit t
+end

lib-rpc/dune

@@ -1,4 +1,4 @@
 (library
  (name ocamlformat_rpc_lib)
  (public_name ocamlformat-rpc-lib)
- (libraries csexp sexplib0))
+ (libraries csexp))