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puffnfresh/roy

Small functional language that compiles to JavaScript.
Source code at GitHub http://roy.brianmckenna.org/
puffnfresh/roy.json
{
  "createdAt": "2011-11-24T21:56:31Z",
  "defaultBranch": "master",
  "description": "Small functional language that compiles to JavaScript.",
  "fullName": "puffnfresh/roy",
  "homepage": "http://roy.brianmckenna.org/",
  "language": "JavaScript",
  "name": "roy",
  "pushedAt": "2014-03-16T20:22:09Z",
  "stargazersCount": 841,
  "topics": [],
  "updatedAt": "2025-08-25T14:58:30Z",
  "url": "https://github.com/puffnfresh/roy"
}

Roy Build Status

Section titled “Roy ”

Roy is a small functional language that compiles to JavaScript. It has a few main features:

  • Damas-Hindley-Milner type inference
  • Whitespace significant syntax
  • Simple tagged unions
  • Pattern matching
  • Structural typing
  • Monad syntax
  • Not-horrible JS output

Usage

Section titled “Usage”

To compile:

make deps
make

To enter a REPL:

./roy

To compile and run a .roy file:

./roy -r examples/helloworld.roy

To compile a .roy file to .js:

./roy examples/helloworld.roy
cat examples/helloworld.js

Example

Section titled “Example”

Input (test.roy):

let addTwo n =
    n + 2


console.log (addTwo 40)

Output (test.js):

var addTwo = function(n) {
    return n + 2;
}
console.log(addTwo(40))

Calling addTwo "test" will result in a compile-time error (addTwo can only take a Number).

See the examples directory for more.

License

Section titled “License”

MIT

Editor Support

Section titled “Editor Support”

Resources

Section titled “Resources”