crforth

A simple FORTH interpreter (http://github.com/russolsen/rforth) ported to the Crystal programming language.

Note that CRForth is an experiment in porting a non-trivial application from Ruby to Crystal. The code is, as I write this, just barely working. This is probably not idiomatic Crystal -- I'm still figuring out what that means.

Some lessons so far:

• Most of the effort of the port involved minor changes to make the static typing happy. For example, FORTH interpreter uses a lot of procs whose return values are ignored. Eventually I had all of them return nil to make the static typing happy. I'm not sure if this is really the correct thing, but it was expediant.

• The original Ruby version used metaprogramming to look at the methods available in a module. I've done that by hand in CRForth because I don't see the equivalent in Crystal.

• It is really cool to get a stand alone, binary executable from Rubyish code.

Installation

Add it to Projectfile

deps do
  github "[your-github-name]/crforth"
end

Usage

require "crforth"

i = CRForth::Interpreter.new
i.run

Or just run the interpreter from source:

crystal src/main.cr

Right now CRForth doesn't have a great interface: It just silently prompts for some FORTH code and executes it. To add 2 + 2 you would do the following:

~/projects/crystal/crforth: make run
crystal src/main.cr
2 2 + . cr
4
bye

Development

There is a Makefile for convenience. The targets are:

• crforth: Build the executable. This is the default.

• clean: Clean up any generated files.

• run: Runs the interpeter from source.

Contributing

1. Fork it ( https://github.com/[your-github-name]/crforth/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• russolsen Russ Olsen (@russolsen) - creator, maintainer