LeanInk is a command line helper tool for Alectryon which aims to ease the integration and support of Lean 4. Alectryon uses the information provided by LeanInk to create a static code visualization for Lean 4 code. For more information about Alectryon make sure to take a look at their repository.

The official version of Alectryon does not yet support LeanInk, as LeanInk is still in active development. Please use our Alectryon Fork to test LeanInk.


You can either build LeanInk and install it yourself as shown below, or you can use the build script to install a LeanInk release version:

sh -c "$(curl https://raw.githubusercontent.com/leanprover/LeanInk/main/init.sh -sSf)"

Building from source

Before you can build LeanInk from source make sure to install the latest version of Lean 4 using elan. This will also automatically install the Lake package manager.

git clone https://github.com/leanprover/LeanInk
cd LeanInk
lake build

To install this built version it is recommended you simply add the LeanInk/build/bin folder to your PATH environment.


Analyzing a simple lean program Input.lean is very straightforward. To do so you simply use the analyze command (shorthand a) and provide LeanInk the input file.

leanInk analyze Input.lean
# OR
leanInk a Input.lean

The analyze command will generate an output file Input.lean.leanInk with the annotate lean program, encoded using Alectryons fragment json format. (For more information about the json format take a look at Alectryon.lean)

If your lean program has external dependencies and uses Lake as its package manager you can use the --lake argument to provide the lakefile.

leanInk analyze Input.lean --lake lakefile.lean

LeanInk will then fetch any dependencies if necessary.

You can also analyze multiple files sequentially (concurrent analysis should be possible but is currently out of scope, feel free to contribute!):

leanInk analyze Input1.lean Input2.lean

This will create Input1.leanink and Input2.leanink respectively. However if you want to provide a lake should be valid for both input files, as you can only provide a single lake file.

To get the supported Lean 4 version of your instance of LeanInk you can do the following:

leanInk leanVersion
# OR
leanInk lV

Usage in Alectryon

Alectryon automatically integrates LeanInk internally to analyze a Lean 4 code file or a documentation file with Lean 4 code blocks. To embed Lean 4 in code blocks you have to use the lean4:: directive for reStructuredText and {lean4} directive for myST markdown files. This is to distinguish the support of Lean 3 and Lean 4 in Alectryon.

For more information about Alectryon make sure to take a look at their repository.



When updating the lean-toolchain, please also:

  • update test/dep/lean-toolchain to match,
  • change the Mathlib commit in test/dep.lakefile.lean to a commit of Mathlib using the same toolchain,
  • run lake update in test/dep/ to update the lake-manifest.json.

Experimental Features

Additional Type Hover Metadata

The following flags are experimental and used to display additional information about a source text token in Alectryon. However this feature in Alectryon is still in active development and available here: AlectryonFork:typeid:

  • --x-enable-type-info flag enables extraction of type information
  • --x-enable-docStrings flag enables extraction of doc strings
  • --x-enable-semantic-token flag enables extraction of semantic toke types for semantic syntax highlighting support

Running Tests

There are some aspects you might want to take note of when attempting to develop a feature or fix a bug in LeanInk.

LeanInk uses simple diffing tests to make sure the core functionality works as expected. These tests are located in the ./test folder.

You can run these tests using lake script run tests. This will run LeanInk for every .lean, that's not a lakefile or part of an lean_package. It will compare the output of LeanInk to the expected output within the .lean.leanInk.expected file.

To capture a new expected output file you can either run lake script run capture to capture the output for all files or use leanInk itself to generate an output for a single file and rename it afterwards. Be sure to carefully examine the git diff before committing the new expected baselines.


LeanInk enforces the same Contribution Guidelines as Lean 4. Before contributing, make sure to read it.

We also highly encourage you to sign your commits.