Alex, yes thank you, the quote-srcloc works at run time, so for example:
(define-syntax (here3 stx)
(let(
[program `(quote-srcloc ,stx)]
)
(datum->syntax stx program)
))
Will print the call point. What the heck is this macro, as it is being passed
the same argument, stx, in both cases (syntax time and run time).
Yep! build-source-location works here.
(define-syntax (here2 stx)
(let(
[a-location (build-source-location stx)]
)
(datum->syntax stx a-location)
))
I hadn't thought to try it because firstly I had expected to find a location
accessor function in the syntax object definition, but also because in section
9.1 of the reference manual none of the many examples given show syntax
objects. And the manual made it sound like it makes syntax objects, but said
nothing it accepting them:
These procedures combine multiple (zero or more) source
locations, merging locations within the same source and
reporting #f for locations that span sources. They also
convert the result to the desired representation: srcloc,
list, vector, or syntax object, respectively.
Greg, syntax/loc is beautiful (so far ;-) it goes beyond my hopes, seems it
shoudl be prominent in the docs.
(define-syntax (messup4 stx)
(syntax/loc stx
(let (
[a 7]
[b 9]
)
(^ a b)
)))
(messup4)
[email protected]> (enter! "test-macro-dev-error.rkt")
test-macro-dev-error.rkt:62:35: ^: unbound identifier in module
in: ^
errortrace...:
context...:
/usr/share/racket/pkgs/errortrace-lib/errortrace/errortrace-
The error message points directly at the caret in the quoted string. (who knows
maybe our programmer thought that meant xor?)
However I don't get the 'immediate'. It did not stop at the let, but descended
to the caret. In your blog post example it descended to the divide - but did
not descend through the begin ??? Is this a varation of the function traceback
not showing tail called functions? I.e. something related to optimization?
When does it descend, and when doesn't it?
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