on bootstrapping: introducing Mes

[Jan Nieuwenhuizen <janneke@gnu.org>]

Hi,

I have a minimal LISP-1.5-resembling interpreter in C that now can
also interpret itself

    https://gitlab.com/janneke/mes

It was inspired by the seemingly often ignored bootstrapping question
made so painfully visible by GuixSD and by OriansJ with their self
hosting hex assembler project.

As a next step after a hex assembler I was thinking of getting Scheme up
and running and use that to create a tiny C compiler, probably using
PEG.  For that I think we need define-syntax, which I had a peek at and
still scares the all-sorts-of-things out of me :-)

I searched for minimal Lisp/Scheme to get that going and found an
article called the Maxwell Equations of Software 1) with a pointer to
the 1962 LISP 1.5 paper by John McCarthy 2).

First I `implemented' Mes/LISP-1.5: the bottom half of page 13 and the
necessary helper procedures defined on pages 8-12 using Guile, removing
all but the primitives needed to run LISP-1.5/Mes (I think): car, cdr,
cond, cons, define, eq?, '()/nil, null?, pair? and quote.  I cheated
with read, and with display and newline for debugging.

Then I translated the program into C and got rid of read by using
getchar/ungetchar.

It's been great fun and now I'm kind of stuck a bit at the point of
implementing macros.  I have a simplistic version in C but want to
remove that again --I like the idea of having the absolute minimal LISP
interpreter in C-- and only introduce macros after having bootstrapped
into the LISP/Mes domain.

Greetings,
Jan

1) http://www.michaelnielsen.org/ddi/lisp-as-the-maxwells-equations-of-software/
2) http://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf
3)

-- 
Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond http://lilypond.org
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