LSP Guide

The dolang-lsp crate provides a Language Server Protocol server for Do, enabling IDE features in any LSP-compatible editor.

Supported Features

Semantic tokens: Syntax highlighting based on the compiler's understanding of the code (not just regex patterns)
Diagnostics: Compile-time errors and warnings reported in real time
Go to definition: Jump to the definition of variables and functions

Running the LSP

The LSP server communicates over stdin/stdout:

dolang-lsp

Configure your editor to use dolang-lsp as the language server for .dol files.

Configuration with `.dolang-lsp.dol`

The LSP searches upward from each file's directory for a configuration file named .dolang-lsp.dol. This file is a Do script that is executed and must return a settings dictionary. Only core modules will be available, so interacting with the external system is not possible, but the returned settings can be programmatically derived.

Prelude Override

The primary use of the config file is to specify the prelude -- the set of imports that the LSP assumes are available in scope. This tells the LSP what names exist so it can provide accurate diagnostics and completions.

The returned dictionary should have a prelude key describing what to import.

# .dolang-lsp.dol
return
  prelude:
    - my_module

Default Prelude

When no .dolang-lsp.dol is found, the LSP defaults to the dolang-shell prelude, which also includes the core language prelude.

When to Use This

The config file is primarily useful for non-dolang-shell projects -- for example, when Do is embedded in a Rust application with custom native functions. It tells the LSP what names your embedding provides so diagnostics don't report false "unbound variable" errors.

For dolang-shell projects, the default prelude is correct and no configuration file is needed.

Execution Environment

The config script runs in a sandboxed VM with strict resource limits (4 MB memory, 250 ms time limit). Compiled config files are cached in ~/.cache/dolang-lsp/bytecode-cache/.