Greetings!
Some weeks ago, I posted a comment [in comp.lang.scheme] on the
implementation of small Scheme systems, including a pointer to a small
LISP interpreter I had written several years ago.
In the past weeks, I have modified the interpreter to make it more LISP-
conformant. Especially, unbound symbols evaluate to NIL now rather than
to themselves. All in all, the language feels more LISP-like.
Of course, the interpreter is still a toy, but I enjoyed the work on
it a lot, and it showed me one more time how powerful even a purely
symbolic LISP dialect is. To show how small the language (not the
implementation) is, here's a dump of the global environment:
QUOTE DEFVAR DEFUN COND EQ NULL ATOM CDR CAR LIST CONS LAMBDA T *F* *T* NIL
The interpreter has grown slightly so that the DOS EXE has a size of
20KB now. The integrated development environment adds another 70KB.
I have re-packaged the interpreter today and it is available at the
(brand-new) LISP section of my homepage. It is called ->LISP and the
package contains the following parts:
* the ALISP interpreter
* a small, text-based IDE (providing an editor, an
evaluation buffer, function trace logs, etc)
* lots of library functions and a few example programs
* the reference manual
Among other things, the function library contains a set of math functions
(PLUS, DIFFERENCE, TIMES, etc) which work in the same way as in the first
LISP implementations: by manipulating lists of digits. Of course, this
approach is not efficient, but very flexible and portable. (To keep things
simple, the domains of the functions have been limited to natural numbers.)
Besides the ->LISP packages, my LISP page carries online versions of
the ->LISP manual and function library, a (not yet finished) lexicon,
and other things mostly related to PureLISP.
Should you wish to visit the page, here's the URL:
http://www.t3x.org/LISP/
Comments and suggestions are welcome.
Bye,
nmh.
--
Nils M Holm <ยทยทยท@t3x.org> -- http://www.T3X.org/