Currently, ocaml-lsp uses a fork of Merlin.
In order to get rid of it, the following patches need to be upstreamed to Merlin:

Monadic IO in dot protocol
We will need to change an interface of merlin_dot_protocol so that it's possible to change the default IO implementation.

Using Spawn instead of Sys.command
Two possible solutions:

• The easier one is to provide a hook, that allows swapping implementation.
• A long-term solution is to move the process management responsibility from merlin library to its consumers.