Re: Implementation of true closures

On 2005-02-04, Rohit Lodha <rohitlodha@gmail.com> wrote:
> Ruby has true closures and I am trying to implement a Virtual Machine
> for it. I have 2 options for effective implementation.


IIRC, there are VM efforts for Ruby, like
http://www.nongnu.org/carbone/
http://rubyforge.org/projects/bytecoderuby/ http://www.atdot.net/yarv/
and PArrot. also see
http://www.rubygarden.org/ruby?VirtualMachineOptions


> 1) Using frame on the heap instead of the stack.


This actually has 2 variants (depending on what you call "the stack" -
I assume it is here the C machine call stack): 1 Allocate each Ruby
frame individually on the heap, in a continuation passing style (See
Appel's book "compiling with continuations" for mre). But this means a
big allocation rate, and requires a good garbage collector. 2 Allocate
each Ruby frame in a Ruby stack (which itself may -or not- be an
object in the ruby heap).


>
> 2) Using setjmp/longjmp and saving state across procedure calls.


    This is what Ruby is doing now (see file ruby/eval.c)


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