README

CrudeMeta Programming Language
==============================

Define your own programming language or DSL in no time!

CrudeMeta is Ruby-based, which means you will use Ruby regular expressions and
Ruby statements to define your DSL.

Hello World in CrudeMeta:

    $ ./crudemeta.rb
    /H/ puts "Hello Crude World!"
    HHH

This will output "Hello Crude World!" three times.  Exit with Ctrl-D or Ctrl-Z.
It uses Ruby's ARGF (using gets) to read specified files and/or stdin.

The semantics are very simple.  CrudeMeta is based on a simple array of Matchers
(Regexp-Block pairs) and starts out with two default Matchers.

The first default Matcher is provided as a fallback and just matches any
character not matched by another Matcher and does nothing.

The second default Matcher looks for:

    /REGEXP/ RUBYCODE

which extends from the first '/' to the end of the line.  This is how a new
Matcher is defined in CrudeMeta.

Whenever crudemeta.rb (Parser.parse) is given a chunk of source code (such as a
line), it looks for the first matching Matcher in the reversed array of Matchers
and executes the associated block.


More examples
-------------

Another hello example:

    /'([^']+)'/ puts "Hello #{m[1]}!"
    'Jim' 'Tom'  'Jane', 'Liz'

Adding up some positive integers: (adding negative Floats left as an exercise)

    /START/ $sum = 0
    /PRINT/ puts $sum
    /\d+/ $sum += m[0].to_i
    START
    10 11 12 13 5 2 99
    PRINT


Tips'n'Tricks
-------------

Use rlwrap to get some fine readline support:

    $ rlwrap ./crudemeta.rb

To get MacOS-X-like pbcopy and pbpaste on Linux, install xclip and define:

    $ alias pbcopy='xclip -selection clipboard'
    $ alias pbpaste='xclip -selection clipboard -o'

Now you can copy'n'paste examples and run them directly (assumes Bash):

    $ pbpaste | ./crudemeta.rb    # or, if you want to also use stdin:
    $ ./crudemeta.rb <(pbpaste) -

To define your funky filter, just do something like this:

    $ edit ~/fu.pre.cm ~/fu.post.cm
    $ alias funky='~/crudemeta.rb ~/fu.pre.cm - ~/fu.post.cm'

E.g. you could put the above /START/ and /PRINT/ and /\d+/ definitions together
with START into fu.pre.cm, and put PRINT into fu.post.cm, to get a filter that
adds up all positive integers from the input with Bignum support.

To get you inspired to mess with the language on a very meta level, consider
this:

    /CLEAR/ @matchers.clear
    CLEAR


Legalese
--------

Copyright (C) 2011 Felix Rabe

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.