Here is a version that works, with explanation following:
#,@(for/list ([i-num (syntax->datum #'n)])
(with-syntax ([i (datum->syntax #'n i-num)])
(format "Test number ~a" i)
(check = i i)))))]))
Your original code converted #'n the syntax object to a compile-time
integer just fine. Here I've called the integer loop variable i-num for
clarity. The step you're missing, as you recognize, is that you need to
introduce i as a pattern variable bound to a syntax object: with-syntax
does the binding, and datum->syntax turns the compile-time integer back
into a syntax object. (I gave it the context from the original #'n, which I
think handles some cases about #%datum transformers and other strange
I also used syntax-parse to conveniently check that n really is a
nonnegative integer literal, though of course you could write such a check
with syntax-case if you really wanted to.
Note that this generates quite a lot of code. I'm assuming there's a good
reason you want to do this with a macro and not a function (perhaps using
with-check-info to enhance failure reporting), but that's certainly
something you'd want to consider if you haven't.
On Fri, Feb 23, 2018 at 7:11 AM, 'Paulo Matos' via Racket Users <
> I am trying to get a macro working to generate an automatic testsuite. I
> have shrank my example to:
> #lang racket
> (define-syntax (gen-testsuite stx)
> (syntax-case stx ()
> [(_ n)
> "Automated suite"
> #,@(for/list ([i (syntax->datum #'n)])
> (format "Test number ~a" i)
> (check = i i))))]))
> (require rackunit
> (gen-testsuite 100))
> This should generate a test-suite that can then be wrapped in run-tests.
> It should example to something like:
> "Automated suite"
> (test-case "Test number 1" (check = 1 1))
> (test-case "Test number 2" (check = 2 2))
> (test-case "Test number 3" (check = 3 3))
> This fails because the i in the body of the test case does not exist at
> run-time. I understand why this is failing. However if I try to replace
> the i by #,(syntax->datum #'i) it also fails. My feeling is that I need
> to introduce a new template variable, which I would generally do with
> with-syntax however I am not sure how to integrate this with the
> for/list expression.
> Paulo Matos
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