Can the ocaml LSP be made to work with _tags file?

Learning
1

I’d like to avoid, for now, using dune to build my ocaml project.

I’m using ocamlbuild, a _tags file to specify dependencies such as the Unix module. Can the ocaml-lsp-server be configured to pick up on that and not report Unix as an unbound module?

2

I don’t know how much of OCaml LSP is related to merlin nowadays.

But if they still are. You can perhaps have that by writing a .merlin file. Here’s an example (note for an ocamlbuild build you rather want B _build/** than what you find in this example).

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3

There is a --fallback-read-dot-merlin option for ocamllsp to do that.

$ ocamllsp --help
ocamllsp [ --stdio | --socket PORT | --port PORT | --pipe PIPE ] [ --clientProcessId pid ]
  --version print version
  --fallback-read-dot-merlin read Merlin config from .merlin files. The `dot-merlin-reader` package must be installed
  --pipe set pipe path
  --socket set the port
  --port synonym for --socket
  --stdio set stdio
  --node-ipc not supported
  --clientProcessId set the pid of the lsp client
  -help  Display this list of options
  --help  Display this list of options
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4

Thank you both.

After installing dot-merlin-reader, passing the --fallback-read-dot-merlin flag to the lsp and dropping the following .merlin file in my project root I have everything running without any Unbound module errors.

PKG unix
B _build/**
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5

Note that you likely also need to add S directive to indicate in which directories sources can be found.

6

Thanks for the heads-up. I already had a few modules compiled in _build and it worked without the Source directive but would have failed on a clean checkout.