exceptions

Hung Jung Lu hungjunglu at yahoo.com
Thu Jun 10 00:57:45 CEST 2004


Alexander Schmolck <a.schmolck at gmx.net> wrote:
> How do younger languages like IO make this point more forcefully than lisp,
> smalltalk etc -- languages which have been around for decades?

Double checked with Lisp just now. And Lisp did not allow me to
redefine "if", "setq", "t", etc. In a sense, Lisp is not keywordless,
whereas Io is truly keywordless. As I said, in Io even "if" and
"while" are implemented as regular functions. In Lisp, you cannot
intercept "if", "setq", etc. In Io, everything is interceptible.
Therefore, Lisp seems not nearly as flexible as Io.

If there are tricks in Lisp to intercept "if", "setq", etc. I'd like
to know. Same if these limitations are specific to some particular
implementations of Lisp. I greatly suspect that these limitations of
Lisp are general, since Lisp does not naturally have prototype-based
scopes like onion-skins, and overriding things like "if" could more
easily create havoc.

regards,

Hung Jung



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