From: Mark Probert <probertm@...>
Date: 2002-12-06T12:17:50+09:00
Subject: Re: [ANN] ratlast 0.1 -- embedded FORTH in Ruby


Hi, Joel.

Joel VanderWerf <vjoel@PATH.Berkeley.EDU> wrote:
>>>>
>>>>t.eval(": linear ( a b -- )  create swap , , does> dup >r @ * r> 4 + @
>>>>+ ;") t.eval("3 17 linear aline") 
>>>
> 
> But closures can do something quite different--they can share a variable 
> binding with the enclosing scope:
> 
> a = 1
> b = 2
> 
> linear = proc { proc {|x|a*x+b} }
> 
This is also (almost) true of the Forth code.  Here, the binding
happens at the line

  3 17 linear aline

I could have written this code:

i = j = 1
until i <= 10
  t.eval("#{i} #{j} linear aline_#{i}")  # rename the fn to avoid conflict
  x = rand(100)
  t.eval("#{x} aline_#{i}")
  puts "x=#{x} : #{i}x + #{j} = #{t.caputure[0]}"
  i += 1
  j += 5
  t.clear
end
    
I think this is the same as closures, or have I misunderstood?

Regards,

-mark.