Skip to content
Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time


Build Status Dependency Status

An extensible linter for OCaml programs. Designed to be used as part of the grading infrastructure for CSCI2041.

Currently, only tested on Linux systems. May work on macOS, but no guarantees are made.


Tagged releases are automatically built as static executables by Travis CI, and uploaded to this repo's releases page. Alternatively, the project can be built from source with the below instructions.

Building from Source


Requires a working Rust installation, which can be obtained with rustup. Requires an installation of OCaml, OPAM, and ocamlfind. Requires a C compiler.

just is recommended, and will be used in the instructions here. It is technically optional, however; one can also run the commands in Justfile by hand.

If compiling a static executable, requires the 4.06.0+musl+static+flambda OPAM switch to be installed. If compiling a dynamic executable, requires the 4.06.0 OPAM switch to be installed. If the OPAMSWITCH environment variable is defined, that switch will be used instead.


Run just package or just package-static. This will compile extlint and its tools, and create the same extlint.tar.gz bundle as built by Travis.


Extract the binaries from extlint.tar.gz to somewhere on your PATH.

Code Organization

get-gitgrade-repos is a small helper program that clones all the student repos. This is mainly for testing and assessments.

ocaml-ast is a hybrid Rust-OCaml crate to parse OCaml code.

rules contains rules developed for linting.

src/json_of_ocaml is a command-line tool that dumps an OCaml untyped AST as JSON. It's the best way to interface with ocaml-ast without linking directly to it.

src/ocaml-syntax-check is a command-line tool that pretty-prints any syntax error in the given file. It's mainly for debugging.

Known Bugs

Due to OCaml Bug #6754, there is a warning about topdirs.cmi when building ocaml-ast.


Licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.