Subject: Re: New Lisp ?
From: (Rob Warnock)
Date: 3 Jan 2002 03:05:29 GMT
Newsgroups: comp.lang.scheme,comp.lang.lisp,comp.lang.functional,comp.lang.dylan
Message-ID: <a10hpp$jel7$>
David Rush  <> wrote:
| Please note: I am talking about a matter of degree here. My biggest
| beef with exception-based systems is that they end up getting used far
| too generally (for unusual code paths rather than actual failure
| handling).

At least as I read it, Kent Pitman's 1990 survey paper on exceptions
suggests that there's nothing wrong with using exceptions for "unusual
code paths":

	It is important to recognize that this distinction between normal
	and exceptional situations is in some sense contrived. Making this
	distinction does not change the way programs behave; it simply
	changes the way we reason about programs--hopefully for the better.
	In some cases, there may be efficiency reasons for considering
	some cases to be exceptional.

In particular, allowing some [presumably infrequent] non-error code
paths to be considered "exceptional" [and using inconspicuous flow
control primitives to access them, such as CATCH/THROW] can, in turn,
allow the "normal" code paths to be considerably simplified without
compromising program correctness.


Rob Warnock, 30-3-510		<>
SGI Network Engineering		<>
1600 Amphitheatre Pkwy.		Phone: 650-933-1673
Mountain View, CA  94043	PP-ASEL-IA

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