A lot of macros start by renaming some syntax that's assumed to
eventually represent a runtime value, like the `or' macro does:
> (syntax->datum (expand-syntax #'(or #t #f)))
'(let-values (((or-part) '#t)) (if or-part or-part '#f))
But it's not always a good thing, particularly when the output will be
processed by another macro, and parts will be tested using an
`identifier=?' function. For example, my `inline-sort' takes `<' as an
argument. So
(inline-sort < a b)
expands to
(let ([lt? <] [temp1 a] [temp2 b])
(if (lt? temp1 temp2) (values temp1 temp2) (values temp2 temp1)))
Well, it did at first. When I discovered that Typed Racket's optimizer
would never detect that `lt?' is actually `<' and replace it with
`unsafe-fl<', I altered the macro to detect when the `<' is an
identifier, and not rename it with a `let'.
I know that I should assert my rights under the Macro Bill. But I like
to program defensively. So what's safe to not rename? I think the
following are:
symbol
number
string
bytes
null
character
regexp
prefab struct key
Also, should I ever have to intern syntax that's one of these kinds of
things?
Neil ⊥
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