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

[Fren Zeee]

On Jul 23, 9:01 am, Fren Zeee <frenz...@gmail.com> wrote:
> 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.

portability does not require VM, it only requires C while emacs
interprets the lisp code. a diff command in C is portable over
computers because its written in C. not because of a VM.