[4.0.0] Remove >> syntax from the PPX

src/ppx/ppx_lwt.ml

@@ -446,32 +446,6 @@ let mapper =
             "Lwt's finally should be used only with the syntax: \"(<expr>)[%%finally ...]\"."
         ))
 
-      | [%expr [%e? lhs] >> [%e? rhs]] as e ->
-        if !sequence then
-          let pat = if !strict_seq then [%pat? ()] else [%pat? _] in
-          let lhs, rhs = mapper.expr mapper lhs, mapper.expr mapper rhs in
-          let op = match e.Parsetree.pexp_desc with
-            | Parsetree.Pexp_apply (op, _) -> op
-            | _ -> assert false
-          in
-          if !debug then
-            Ast_helper.Exp.attr
-              ([%expr
-                let module Reraise = struct external reraise : exn -> 'a = "%reraise" end in
-                Lwt.backtrace_bind
-                  (fun exn -> try Reraise.reraise exn with exn -> exn)
-                  [%e lhs]
-                  (fun [%p pat] -> [%e rhs])
-              ] [@metaloc lhs.pexp_loc])
-              (Ast_mapper.attribute_of_warning op.Parsetree.pexp_loc
-                "The operator >> is deprecated")
-          else
-            Ast_helper.Exp.attr
-              [%expr (Lwt.bind [%e lhs] (fun [%p pat] -> [%e rhs]))]
-              (Ast_mapper.attribute_of_warning op.Parsetree.pexp_loc
-                "The operator >> is deprecated")
-        else
-          default_mapper.expr mapper expr
       | { pexp_desc = Pexp_apply (fn, args); pexp_attributes; pexp_loc } when !log ->
         default_loc := pexp_loc;
         lwt_log mapper fn args pexp_attributes pexp_loc
@@ -511,11 +485,11 @@ let args =
 
     "-no-sequence",
       Unit no_sequence_option,
-      " disable sequence operator (deprecated)";
+      " has no effect (deprecated)";
 
     "-no-strict-sequence",
       Unit no_strict_sequence_option,
-      " allow non-unit sequence operations (deprecated)";
+      " has no effect (deprecated)";
   ])
 
 let () =

src/ppx/ppx_lwt.mli

@@ -191,37 +191,6 @@ $ ocamlfind ocamlc -package lwt.ppx \
     -ppxopt lwt.ppx,-no-debug -linkpkg -o foo foo.ml
  v}
 
-   {2 Sequence}
-
-   With OCaml 4.04.0 and on a convenient syntax is available for sequencing Lwt
-   operations using [;%lwt].  This allows free mixing of standard [;]
-   sequencing and [;%lwt] sequencing without extra parentheses:
-   {[
-     let i = ref 0 in
-     write stdout "Hello, ";%lwt
-     incr i;
-     write stdout "world!"
-   ]}
-
-   It is also possible to sequence Lwt operations with the [>>] operator:
-   {[
-     write stdout "Hello, " >> write stdout "world!"
-   ]}
-
-   By default, each operation must return [unit Lwt.t]. This constraint can be
-   lifted with the option [-no-strict-sequence]. The operator can be disabled
-   with the option [-no-sequence].
-
-   If you are mixing `>>` and `;`, you need to use parentheses or `begin`/`end`
-   to get the result you expect:
-
-   {[
-     write stdout "Hello, " >> (ignore (); write stdout "world!")
-   ]}
-
-   Note that unlike [>>=], [>>] is not an OCaml value. it is a piece of syntax
-   added by the ppx rewriter - i.e., you cannot refer to [(>>)].
-
    {2 Logging}
 
    The logging syntax extension is enabled with [-log].

test/packaging/jbuilder/ppx/user.ml

@@ -1,3 +1,6 @@
 let () =
-  let p = Lwt.return () >> Lwt.return () in
+  let p =
+    let%lwt () = Lwt.return () in
+    Lwt.return ()
+  in
   ignore p

test/packaging/ocamlfind/ppx/Makefile

@@ -3,9 +3,6 @@ test : clean
 	ocamlfind opt -package lwt_ppx -c user.ml
 	ocamlfind opt -package lwt -linkpkg user.cmx
 	./a.out
-	# Expecting failure with "Unbound value >>":
-	! ocamlfind opt -package lwt_ppx \
-	    -ppxopt lwt_ppx,-no-sequence -c user.ml
 
 .PHONY : clean
 clean :

test/packaging/ocamlfind/ppx/user.ml

@@ -1,3 +1,6 @@
 let () =
-  let p = Lwt.return () >> Lwt.return () in
+  let p =
+    let%lwt () = Lwt.return () in
+    Lwt.return ()
+  in
   ignore p

test/ppx/main.ml

@@ -155,14 +155,6 @@ let suite = suite "ppx" [
          return !x
     ) ;
 
-  test "sequence"
-    (fun () ->
-       let lst = ref [] in
-       (lst := 2 :: !lst; Lwt.return_unit) >>
-       (lst := 1 :: !lst; Lwt.return_unit) >>
-       (Lwt.return (!lst = [1;2]))
-    ) ;
-
   test "structure let"
     (fun () ->
        let module M =