Bun Setup

This guide covers using typesugar with Bun.

Current Status

Bun has its own TypeScript transpiler that doesn't support TypeScript transformer plugins. This means typesugar macros don't work with Bun's native transpiler.

However, you can still use typesugar with Bun by using a build step.

Workaround: Pre-compile with tsc/Vite

Option 1: Use typesugar CLI for development

# Build with typesugar
bunx typesugar build

# Run the compiled output
bun dist/index.js

Option 2: Use Vite for bundling

// vite.config.ts
import { defineConfig } from "vite";
import typesugar from "unplugin-typesugar/vite";

export default defineConfig({
  plugins: [
    typesugar({
      // Typecheck expanded output (since Vite doesn't typecheck)
      strict: true,
    }),
  ],
  build: {
    target: "esnext",
    outDir: "dist",
    lib: {
      entry: "src/index.ts",
      formats: ["es"],
    },
  },
});

# Build with Vite
bun run vite build

# Run with Bun
bun dist/index.js

Project Setup

package.json

{
  "scripts": {
    "build": "typesugar build",
    "dev": "typesugar watch",
    "start": "bun dist/index.js"
  },
  "devDependencies": {
    "@typesugar/transformer": "^0.1.0",
    "ts-patch": "^3.0.0",
    "typescript": "^5.0.0"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "Bundler",
    "outDir": "./dist",
    "plugins": [{ "transform": "@typesugar/transformer", "type": "program" }]
  }
}

Testing with Bun

For tests, you have two options:

Option 1: Pre-compile test files

# Build tests first
typesugar build --project tsconfig.test.json

# Run compiled tests with Bun
bun test dist/

Option 2: Use Vitest

Vitest works with Bun and supports the typesugar plugin:

// vitest.config.ts
import { defineConfig } from "vitest/config";
import typesugar from "unplugin-typesugar/vite";

export default defineConfig({
  plugins: [typesugar()],
  test: {
    include: ["src/**/*.test.ts"],
  },
});

bunx vitest

Future Support

Bun has an open issue for supporting TypeScript transformer plugins. When this lands, typesugar will work natively with Bun's transpiler.

In the meantime, the build-step approach works reliably and maintains full type safety.

Troubleshooting

"comptime is not a function"

This error means Bun ran your TypeScript directly without macro expansion. Use the build step as described above.

Slow builds

For faster iteration:

1. Use typesugar watch for incremental builds
2. Only rebuild changed files
3. Consider using Vite's dev server for web projects

Next Steps

• Vitest Setup for testing
• Editor Setup