fuby

Functional Ruby

Fuby is a hybrid functional/object-oriented programming language with the same syntax as Ruby, although pretty different semantics in many aspects.

It targets the Rubinius VM, so you need to install Rubinius to run it.

It is just an idea for now. Some of its features might or might not be:

• Pervasive immutability
• Controlled IO
• Methods as first-class functions
• [Some] laziness
• Monads

Keep checking this repository for new ideas, code examples and so on :)

Features

Fuby starts out as a fully compliant Ruby interpreter, and as I develop more and more, its semantics will differ more and more from Ruby, normally in backwards incompatible ways. Here's what's implemented for now:

Immutable strings

All strings are instances of Fuby::String, which is an immutable kind of String.

Variables are not reassignable

Variables cannot be reassigned a different value.

a = 3
a = 5 # will raise a Fuby::CompileError

Real pattern matching

Pattern matching is implemented in case statements. If you want to match in the old ruby style, with procs or regexes or classes, you still can:

case 1
when Integer
  3
else
  10
end
# => 3

But the interesting part is matching predicates that will bind variables inside the when body:

case 1
when x.odd?
  x + 2
else
  10
end
# => 3

And the best is that it works with any destructurable sequence. And you can ignore a certain value with _:

case [100, 2, :foo]
when Integer, x.even?, _
  x + 1
else
  10
end
# => 3

Installation

After installing Rubinius, install Fuby as a gem:

$ gem install fuby

Usage

$ fuby my_program.fb

Who's this

This was made by Josep M. Bach (Txus) under the MIT license. I'm @txustice on twitter (where you should probably follow me!).