Re: What's the spec for emacs lisp virtual machine ?

[Fren Zeee]

On Jul 23, 8:59 am, Fren Zeee <frenz...@gmail.com> wrote:
> On Jul 23, 1:34 am, p...@informatimago.com (Pascal J. Bourguignon)
> wrote:
>
>
>
> > Fren Zeee <frenz...@gmail.com> writes:
> > > What's the spec for emacs lisp virtual machine ?
>
> > The source code of emacs.
>
> > > Where are the complete set of virtual machine commands ?
>
> > In src/bytecode.c
>
> > > Where is the theory for such a virtual machine in the clearest
> > > description ? (not general theory, but one applicable directly to
> > > understanding emacs vm.)
>
> > It's really quite a simple VM.  Just read the sources!
>
> > > Does the emacs lisp operate as a stack push/pop or as parsing ?
>
> > emacs lisp works like any other lisp.  There's an abstract 'eval' that
> > interprets it.  Any good course about lisp would introduce it.
>
> > > Why is a VM needed when there is compiled C code running machine
> > > code ?
>
> > Is this home work?
>
> > Search the sources of emacs for compilers.
> > How many compilers do you find?
> > What are their source files?
> > What machine do they target?
>
> > > How do you implement a LISP interpreter using a stack based and syntax
> > > tree methods ?
>
> > Interpretation may be done without any consideration on the underlying
> > architecture.
>
> > > Some overview with concrete examples please, but of practical value.
>
> > Perhaps you should not limit yourself to emacs lisp.  Allow yourself
> > to read also about other lisps, including scheme.  
>
> > You could also check the sources of various other Lisp, including:
> > - sbcl or ccl,
> > - clisp, and
> > - ecl
> > to answer the above questions for them as well as for emacs lisp.
>
> > There's a lot of material out there.  You could start with:
>
> >  http://www.informatimago.com/develop/lisp/small-cl-pgms/aim-8/
> >    (that paper contains the original LISP interpreter).
>
> > Googling for: lisp in lisp
> > gives good results such as:
>
> >  http://lib.store.yahoo.net/lib/paulgraham/jmc.lisp
>
> >  http://www.softwarepreservation.org/projects/LISP/
>
> >  http://www.schemers.org/Documents/Standards/R5RS/HTML/r5rs.html
> >    (this report contains (part of) formal specifications of scheme).
>
> > > Also, for either you need a scanner and so an example of a scanner
> > > using a transition table. How do you decide on the states that are
> > > minimal and not redundant ?
>
> > > What is the difference between a stack architecture of a processor and
> > > register based one ?
>
> > Get a description of a stack architecture.
> > Get a description of a register based processor.
> > Compute the differences.
>
> > If you're lazy, as it seems you are, you could just
> > use google:  stack vs register VM
>
> > > wouldnt the former still need an ALU and indirect
> > > addressing to do the job ?
>
> > What do you think?
>
> > > A diagram and some explanation, or else we
> > > will be in the domain of linguistic ambiguity.
>
> > Or even better, use formal specifications for the various kind of VM,
> > and a formal specification of Lisp, and show how you can map the later
> > to each one of the formers.
>
> > > Upload a hand sketched image if necessary, or a reference to specific
> > > pages in google books.
>
> > > I have done searches on wiki and other places but the things are not
> > > entirely clear because they are not oriented to my goal of centering
> > > around emacs.
>
> > You need to read LiSP, which covers how to implement Lisp.
>
> > LiSP   = "Lisp in Small Pieces"  
> >          http://www-spi.lip6.fr/~queinnec/WWW/LiSP.html
> >          This book covers Lisp, Scheme and other related dialects,
> >          their interpretation, semantics and compilation. To sum it up
> >          in a few figures: 500 pages, 11 chapters, 11 interpreters and
> >          2 compilers.
>
> > --
> > __Pascal Bourguignon__                    http://www.informatimago.com/
>
> unfortunately, this reply did not give any benefit and info repeated
> before. the reply did not even put a snippet of the code from c file
> to illustrate how he himself read and understood it. someone else try
> if anyone knows.

I already read and understood jmc's doc. he does nt seem to understand
the difference between stack based and tree based parsing.