Duso VSCode Extension

Language Server Protocol (LSP) support for Duso in VSCode.

⚠️ Requires Duso Installation

The LSP features (error diagnostics, hover documentation, go to definition, find references) require the duso binary to be installed on your system. Visit duso.rocks for installation instructions.

Features

• Syntax Highlighting - Color coded syntax for Duso scripts
• Error Diagnostics - Real-time parse error detection
• Hover Documentation - View built-in function documentation
• Go to Definition - Jump to function and variable definitions (Ctrl+Click)
• Find References - Find all usages of variables and functions

Installation

From Source (Development)

cd vscode
npm install
code --extensionDevelopmentPath=. .

This opens a new VSCode window running the extension in development mode.

Prerequisites

Ensure the duso binary is in your PATH:

which duso
duso --version

If duso is not found, the extension will fail to start. Make sure you've run ./build.sh in the project root.

Quick Test

1. Create a file test.du:

   print("Hello, Duso!")
   
   function greet(name) do
     print("Hello, " + name)
   end
   
   greet("World")
   

2. Open the file in VSCode - you should see syntax highlighting

3. Hover over print and greet to see documentation

4. Ctrl+Click on greet("World") to jump to the function definition

5. Create a syntax error to see diagnostics:

   print(1 2)  # Missing comma
   

Features

Error Diagnostics

• Syntax errors shown in real-time with red squiggles
• Error details in the Problems panel

Hover Documentation

• Hover over built-in functions (print, len, map, etc.) to see docs
• Shows function signatures and descriptions

Go to Definition

• Ctrl+Click on a function/variable to jump to its definition
• Works for same-file definitions in Phase 1

Find References

• Right-click → Find All References to find all usages
• Highlights all matching identifiers

Architecture

The extension launches duso -lsp which:

1. Reads LSP messages from VSCode over stdin
2. Parses documents and analyzes them
3. Sends diagnostics, hover info, and definitions back to VSCode

No separate server needed - it's built into the duso binary!

Troubleshooting

If the server doesn't start:

1. Check Output panel: View → Output → Duso Language Server
2. Verify duso is in PATH: which duso
3. Rebuild: ./build.sh in project root
4. Reload extension: Cmd+Shift+P → Developer: Reload Window

Phase 1 Implementation

Currently implemented:

• ✅ Syntax highlighting
• ✅ Error diagnostics
• ✅ Hover documentation
• ✅ Go to definition (same-file)
• ✅ Find references (same-file)

Coming in Phase 2:

• Code completion
• Document symbols (outline)
• Rename refactoring
• Cross-file definitions