Would it work to have your code expand into uses of
with-unquote-rewriter that chained things together?
Alternatively, I wouldn't mind if something like that were folded into
Redex itself and with-unquote-rewriters left as part of the public API
for backwards compatibility reasons.
And one other thought: I generally have discouraged the use of unquote
rewriters in favor of writing little meta-functions (whose body uses
unquote) and then using compound rewriters to adjust the metafunction
calls. Does that work well in your use cases?
Robby
On Sun, Aug 23, 2015 at 5:27 PM, Matias Eyzaguirre wrote:
> To get rid of racket expressions that have been embedded in metafunctions and
> reduction relations, you use `with-unquote-rewriter`, but you can currently
> only have one rewriter active at a time (as underneath it's a single
> parameter that holds a function).
>
> I've been writing a little library to make working with rewriters a little
> more friendly, I expose a rewriter stack that you can push and pop atomic and
> compound rewriters to. I've been thinking about how best to add support for
> unquote rewriters, but I'm stumped.
>
> One possibility that occurred to me was to have pushing an unquote rewriter
> procedure RW onto the stack just set the current unquote rewriter to a
> function that calls RW on the lw in question, and if RW produces an lw where
> the unq? field is true, then that is the result, otherwise use the previous
> unquote rewriter (thus rewriters that don't want to make a change pass
> responsibility up the stack). Other than the fact that this could get rather
> slow when the unquote-rewriter stack gets really deep, redex currently
> doesn't publicly export the current-unquote-rewriter parameter. Would it be
> possible to make that change?
>
> In the meantime I suppose I shall make my own parameter for keeping track of
> unquote-rewriters, though this has the disadvantage of not knowing anything
> about unquote-rewriters set with the with-unquote-rewriter macro.
>
> Another thought that would require more effort, why is there only ever a
> single unquote-rewriter at a time? compound-rewriters and atomic-rewriters
> both have a table, allowing multiple rewriters to be layered on top of each
> other?
>
> Anyway thanks,
> Matias Eyzagurre.
>
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