markf@zurich.ai.mit.edu (Mark Friedman) (06/17/91)
In article <2154@sheol.UUCP> throopw@sheol.UUCP (Wayne Throop) writes:
A thought that occurs to me is that the rapid adoption of perl in the
Unix community is a back-door defection to a philosophy that Lisp folks
have been preaching for years. In perl, one is partly abandoning the
the notion of small, stand-alone tools that do one thing well, and
instead adopting the monolithic everything-in-one-language approach that
Lisp has always had. You know. "Swiss army chainsaw." Perl simply
makes this palatable to the Unix community by leaving out some of the
parenthesis and including a baroque syntax and idiosyncratic semantics. :-)
Although I understand why many people think of Lisp (esp. Common Lisp)
as a "Swiss army chainsaw", Lisp folks do not, on the whole, preach
the philosophy that you are crediting them with. On the contrary,
Lisp folks have very much espoused the small, do-one-thing-well
approach. A well designed, well programmed Lisp procedure does one
thing well. This, of course, is simply good modular programming.
The "stand-alone" part is where Lisp has sort of failed so far, unless
you consider that Lisp procedures stand alone in the Lisp environment.
As an aside, I also find it interesting that "everybody" seems to have
implemented or be implementing a tiny language or two, even if they
later repent. I don't know if that's good, bad, or indifferent,
but it seems to be so.
This is also a philosophy preached by Lisp folks for years. Large
programs are considered as the creation of application specific
languages. I think that it is good.
Finally, I note that I'm familiar with at least one alternative to the
"brutal stripping" of syntax to allow the "outer interpreter" (eg: the
shell) to smoothly encapsulate several "inner interpreters" (eg:
commands with mini-languages in their arguments, like expr, grep, and so
on and on). It is, however, somewhat trickier.
Instead of giving symbols no interpretation at all, you can give them
*lexical* significance, but no *semantic* significance. You can get
away with this because the lexical significance of characters is pretty
standard across languages. For example, () always match, and so on.
One also has to have a regular and predictable quote convention to deal
with the few leftover conflicts, sigh. But one almost always has to
have some moral equavilent of this, even in "brutally stripped"
syntaxes.
Lisp is nice in this regard because you can leverage on the Lisp
reader which matches the parentheses, handles the quoting, etc. You
can also utilize the Lisp macro facility which is a standard and
powerful machanism for language extension and creation.
-Mark
--
Mark Friedman
MIT Artificial Intelligence Lab
545 Technology Sq.
Cambridge, Ma. 02139
markf@zurich.ai.mit.edu