Language Server Index Format for OCaml

Export OCaml type hovers and jump-to-definitions in LSIF

Note: development is early work-in-progress; the tool is released in the interest of early adopters who may find it immediately useful for open source projects.

What is LSIF?

The Language Server Index Format (LSIF) is a format for storing code intelligence data like type hovers and jump-to-definitions. See LSIF and how it relates to LSP for more details. Platforms like Sourcegraph use LSIF to surface this information in your browser.

Quickstart : generate LSIF dump

1. Pin and install opam pin add merlin-lsif https://github.com/rvantonder/merlin.git\#lsif. This installs an extension of merlin that dumps type and definition data. Installing merlin-lsif will not conflict with existing merlin installations.

2. Pin and install opam pin add lsif-ocaml https://github.com/rvantonder/lsif-ocaml.git

3. Compile your OCaml project. Note: lsif-ocaml depends on .merlin files to work

4. At the root of your directory, run lsif-ocaml-dump

5. Run lsif-ocaml -only-type-hovers > data.lsif

6. Optionally delete the *.lsif.in files in your repository with find . -name *.lsif.in | xargs rm, or keep them around and update your data.lsif for changed files in new commits.

FAQ

Generating LSIF takes a while, how can I make it faster?

Initially generating an LSIF file can take some time (20 minutes on a Macbook for large projects). You can speed it up with lsif-ocaml-dump -p to generate *.lsif.in files in a (less stable) parallel frenzy. Note that once every .ml* file is processed, *.lsif.in files only need to be updated for changed files. Easily regenerate a smaller number of files by running lsif-ocaml-dump in subdirectories, or with, e.g.,:

cat updated-file.ml | ocamlmerlin-with-lsif server lsif update-file.ml -dot-merlin ./path/where/update-file/lives/.merlin > updated-file.ml.lsif.in