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[Scheme-reports] Return value for unmatched cond-expand
- To: scheme-reports@x
- Subject: [Scheme-reports] Return value for unmatched cond-expand
- From: Christian Stigen Larsen <csl@x>
- Date: Wed, 2 Jan 2013 00:25:52 +0100
Draft 8 does not say whether the return value for an unmatched cond-expand
For example, in Chibi,
evaluates to #t.
Meanwhile, the example cond-expand macro on page 72 explicitly tests for no
(syntax-error "Unfulfilled cond-expand"))
This could be important for portability:
Some implementations could conceivably not match on any clauses on code
without an else-clause. I'm just saying that it *could* have adverse
effects, but being explicit about it in the text could fix that.
Should you agree, then perhaps a good place for such a note could be in the
following passage on page 15:
"[...] Otherwise, the cond-expand has no effect. Unlike cond,
cond-expand does not depend on the value of any variables."
Christian Stigen Larsen
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