Millet
Standard ML (SML) support for VS Code.
Millet analyzes SML code without running it, and provides information like:
- Syntax highlighting
- Bracket and comment configuration
- Snippets
- Inline diagnostics
- Hover for type/documentation
- Inlay hints
- Jump to definition
- Code completions
- Code actions
- Document symbols
- Find all references
Millet also supports SML/NJ Compilation Manager (CM) and ML Basis (MLB), allowing for analysis of multi-file SML projects.
Note that Millet does not actually run SML code. To do that, you'll need an installation of SML, like SML/NJ or MLton.
- Check out the blog post introducing the project.
- Refer to the manual for information about setup, configuration, and features.
- See the full documentation for other information, like explanations for diagnostics and project policies.
Usage
First, install the extension, and open VS Code on a folder with SML files.
If VS Code does not automatically detect how to analyze the project, add a millet.toml that defines the "root" of the project. All files should be reachable from this root.
To define the root, set workspace.root in millet.toml to the path to a file that lists out all the SML files Millet should analyze. This file should be either:
MLB and CM are the two most common ways of managing large SML projects with many files.
In the example below, we've opened VS Code to a folder with 4 files: a Millet config file, a "root" file with MLB syntax, and two SML files.
millet.toml
version = 1
workspace.root = "sources.mlb"
sources.mlb
a.sml
b.sml
a.sml
(*!
* `increment x` returns one more than `x`.
*)
fun increment x = x + 1
b.sml
val four = increment 3
val () = "if you see a type error, Millet is working!"
Millet is affiliated with Project Savanna, a project whose goal is to improve tooling for Standard ML.
There is a Discord server for Project Savanna. The server has a channel for Millet support and discussion.
