Firefly Compiler

0.6.19 verified Fri May 01 auth: no javascript

A compile-to-JavaScript language with colorless async/await and type classes. Current stable version is 0.6.19, with frequent releases (multiple self-hosting milestones). Self-hosting compiler written in JavaScript compiles itself in ~1.2 seconds. Differentiators: colorless async (no explicit async/await markers), type classes (similar to Haskell), and self-hosting transpiler approach. Targets Node.js >=18. Active development with contributions from multiple developers.

Common errors

error ERR_REQUIRE_ESM: require() of ES Module /path/to/firefly-compiler/index.js from /path/to/your/file.js not supported. ↓

cause Package is ESM-only; CommonJS require() is not allowed.

fix

Replace require('firefly-compiler') with import firefly from 'firefly-compiler' or switch to dynamic import.

error SyntaxError: Unexpected token 'export' ↓

cause Node.js version <18 does not support ESM syntax without --experimental-modules flag.

fix

Update Node.js to >=18 or use a transpiler like Babel.

error Error: Cannot find module 'firefly-compiler' ↓

cause Package not installed or not in node_modules.

fix

Run npm install firefly-compiler (requires Node.js >=18).

Warnings

breaking Node.js >=18 required; older versions will fail with syntax errors due to ESM. ↓

fix Upgrade Node.js to version 18 or higher.

gotcha Package is ESM-only; using require() will throw ERR_REQUIRE_ESM. ↓

fix Use import statements instead of require() in your project, or switch to dynamic import.

gotcha Compilation may fail if source contains unsupported features from newer Firefly versions. ↓

fix Check changelog for breaking syntax changes. Use --version flag to see compiler version.

deprecated Older versions (<0.5) used a different API; compile function may not exist. ↓

fix Upgrade to latest version and use compile() from the package.

Install

npm install firefly-compiler

yarn add firefly-compiler

pnpm add firefly-compiler

Imports

default import

wrong

const firefly = require('firefly-compiler')

correct

import firefly from 'firefly-compiler'

Package is ESM-only. CommonJS require() will fail.

compile function
```
import { compile } from 'firefly-compiler'
```
Named export compile is available. Use default import if you want the whole compiler object.
TypeScript types
```
import type { FireflyOptions } from 'firefly-compiler'
```
TypeScript types are included. Use type import for compile-time only types.

Quickstart

Compiles a simple Firefly snippet that prints a message, then executes the generated JavaScript.

import { compile } from 'firefly-compiler';

const source = `
print("Hello from Firefly!")
`;

async function main() {
  const { code } = await compile(source, { target: 'es2022' });
  eval(code);
}

main().catch(console.error);