From: Mark Probert <probertm@...>
Date: 2002-12-06T05:57:53+09:00
Subject: [ANN] ratlast 0.1 -- embedded FORTH in Ruby


Rubyists,

Later on today, I will be uploading the first release of
ratlast to RAA.  You can get the system at

   http://www3.sympatico.ca/mark.probert/download/files/ratlast_0_1.tar.gz

(This is my home account which I don't have access to at work.
I will upload the file around 19.00 EST.)


*** What is ratlast?

ratlast is an extension gives Ruby the power and flexibility of FORTH,
using John Walker's ATLAST system.

ATLAST is a F-83 style system that includes floating point
and string primitives, as well as systems FORTH standards such
as CREATE and DOES>.  It is very powerful, flexible, fast, and
easy to extend.  On the fly compiling is trivial.

Most of all, it is a -lot- of fun to use!

*** Example

Here is a little magic :-).  We create a linear equation ax+b and
give it the name 'linear'.  For the example, we know the slope (3)
and intercept (17) and the x varies.  We then evaluate the function
and print the result.

(For the FORTHists in the audience, the stack is 4-bytes wide for
all integers, hence the 4 + ...)

$ cat ex1.rb
require 'Atlast'
t = Atlast.new

t.eval(": linear ( a b -- )  create swap , , does> dup >r @ * r> 4 + @ + ;")
t.eval("3 17 linear aline")
x = 1
until x >= 10
     t.eval("#{x} aline .")
     puts "x=#{x} : 3x + 17 = #{t.capture[0]}"
     x += 1
     t.clear      # clear the capture buffer
end

*** Output

$ ruby ex1.rb
x=1 : 3x + 17 = 20
x=2 : 3x + 17 = 23
x=3 : 3x + 17 = 26
x=4 : 3x + 17 = 29
x=5 : 3x + 17 = 32
x=6 : 3x + 17 = 35
x=7 : 3x + 17 = 38
x=8 : 3x + 17 = 41
x=9 : 3x + 17 = 44



-mark.