Depends on what `x` is, both symbolically and in terms of binding:
(for/first ([(list _) #hash([(a) . 1])])
list)
(define-match-expander x
(syntax-rules ()
[(_ pat) (list pat)]))
(match '(ok)
[(x v)
v])
-Philip
On Fri, Nov 23, 2018 at 11:41 PM Greg Hendershott <greghendersh...@gmail.com>
wrote:
> > The trouble, sadly, is that this grammar is ambiguous. In
> >
> > (for ([(x y) s])
> > ....)
> >
> > should (x y) be parsed as a single match pattern or as two binders for a
> two-valued sequence (such as one produced by in-hash, for example)?
>
> Unless I'm being dense, (x y) isn't a valid single match pattern?
>
> [Quasipatterns like `(x y) or `(,x ,y) would be.]
>
> But even if it is grammatically possible, like I said at the end, I'm
> not sure it's worthwhile.
>
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