What's your setup for OCaml development?

When I typing OCaml, VScode could not indent automatically, with my config as follows:

    "reason.path.ocamlmerlin": "/Users/taki/.opam/4.05.0/bin/ocamlmerlin",
    "editor.formatOnSave": true,
    "editor.formatOnType": true,
    "reason.diagnostics.tools": [
        "merlin",
    ],