Duso VSCode Extension

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

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