Hew Language Support for VS Code

Syntax highlighting and language support for the Hew programming language — a high-performance, network-native, actor-based language.

Features

• Full syntax highlighting for Hew language constructs
• Language Server Protocol — completion, hover, definition, document symbols, semantic tokens, diagnostics (requires hew-lsp)
• Document formatting — format on save via hew fmt (requires hew CLI)
• Actor declarations — actor, receive fn, receive, init, terminate
• Supervisor trees — supervisor, child, restart, budget, strategy
• Structured concurrency — scope, spawn, await, select, join
• Generators — gen fn, async gen fn, yield, cooperate
• Wire types — wire type, wire enum, field tags with @
• Traits and generics — trait, impl ... for, type parameters [T: Send]
• Pattern matching — match, =>, guards, destructuring
• All built-in types — i8–i64, u8–u64, f32, f64, bool, char, string
• String variants — regular "...", raw r"...", byte b"...", interpolated f"...{expr}...", char 'x'
• Duration literals — 100ms, 5s, 1h
• Comments — //, /* */, /// (doc comments)
• Auto-closing pairs for brackets, braces, parentheses, strings
• Code folding and bracket matching

Example

actor Counter {
    var count: i32 = 0;

    receive fn increment() {
        self.count = self.count + 1;
    }

    receive fn get() -> i32 {
        self.count
    }
}

supervisor CounterSupervisor {
    child counter: Counter
        restart(permanent)
        budget(5, 30s)
        strategy(one_for_one);
}

fn fibonacci(n: i32) -> i32 {
    if n <= 1 {
        n
    } else {
        fibonacci(n - 1) + fibonacci(n - 2)
    }
}

fn main() -> i32 {
    let result = fibonacci(10);
    println(result);
    0
}

Installation

From VSIX (local install)

1. In the extension directory, run:

   npm run package
   

2. In VS Code, open the command palette (Ctrl+Shift+P) and run: Extensions: Install from VSIX...
3. Select the generated .vsix file

From source (development)

1. Clone this repository
2. Run npm install && npm run build:dev
3. Open this folder in VS Code and press F5 to launch the Extension Development Host

Configuration

Workspace-built hew and hew-lsp binaries are only auto-selected in trusted workspaces by default. In Restricted Mode, trust the workspace or set hew.allowUntrustedWorkspaceBinaries in user settings to opt in.

Debugging

Before launching a Hew debug session:

• If program points to a .hew source file, make sure hew.debugger.hewPath is set or hew is on PATH so the extension can run hew build --debug.
• Make sure the selected backend executable is on PATH:
  • debuggerBackend: "auto" picks lldb-mi on macOS and gdb elsewhere.
  • debuggerBackend: "lldb" requires lldb-mi.
  • debuggerBackend: "gdb" requires gdb.

Example .vscode/launch.json:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "hew",
      "request": "launch",
      "name": "Debug Hew Program",
      "program": "${workspaceFolder}/main.hew",
      "debuggerBackend": "auto"
    }
  ]
}

If preflight reports that a backend is unavailable, either install the required tool or switch debuggerBackend to a backend that is already installed on your system.

Supported Token Scopes

License

Licensed under the Apache License, Version 2.0. See LICENSE for details.