`ocamlmerlin single type-enclosing` stopped producing Reason syntax

[anmonteiro]

The following cram test produces different results in OCaml versions <= 5.2 vs OCaml >= 5.3.

The merlin versions are v5.3-502 and v5.4-503.

  $ cat >dune-project <<EOF
  > (lang dune 3.20)
  > EOF
  $ cat >dune <<EOF
  > (executable (name foo))
  > EOF
  $ cat > foo.re <<EOF
  > let _x = List.map;
  > EOF

  $ dune build
  $ ocamlmerlin single type-enclosing -position 1:15 -verbosity 0 -filename foo.re < foo.re | jq '.value[0]'
  {
    "start": {
      "line": 1,
      "col": 9
    },
    "end": {
      "line": 1,
      "col": 17
    },
    "type": "('a => 'b, list('a)) => list('b)",
    "tail": "no"
  }

With OCaml 5.3+, the diff is no longer in Reason syntax:

@@ -19,7 +19,7 @@
       "line": 1,
       "col": 17
     },
-    "type": "('a => 'b, list('a)) => list('b)",
+    "type": "('a -> 'b) -> 'a list -> 'b list",
     "tail": "no"
   }