[racket-dev] Constructing an identifier to an unexported binding

Essentially yes.  It doesn't do anything else, but it needs an identifier
to do it.  Currently, TR starts with a module and a symbol, goes through an
expensive process to forge an identifier from them, just to call
free-identifier=? to compare based on the module and the symbol after all.
Doing the comparison directly, without ever forging the identifier, would
be quicker.

On Thu, May 23, 2013 at 8:43 PM, Eric Dobson <eric.n.dobson at gmail.com>wrote:

> Isn't that exactly what free-indentifier=? is checking for on
> identfiers with a module level binding? Or is there something else it
> does?
>
> On Thu, May 23, 2013 at 3:13 PM, Carl Eastlund <cce at ccs.neu.edu> wrote:
> > On Thu, May 23, 2013 at 4:13 PM, Ryan Culpepper <ryanc at ccs.neu.edu>
> wrote:
> >>
> >> On 05/23/2013 01:57 AM, Eric Dobson wrote:
> >>>
> >>> Some modules have macros which expand into identifiers that are not
> >>> exported, as they want to protect those bindings. TR currently has the
> >>> following code which allows it to generate an identifier which is
> >>> free-identifier=? to what would appear in the output of the macros.
> >>>
> >>> define (make-template-identifier what where)
> >>>    (let ([name (module-path-index-resolve (module-path-index-join where
> >>> #f))])
> >>>      (parameterize ([current-namespace (make-empty-namespace)])
> >>>        (namespace-attach-module (current-namespace) ''#%kernel)
> >>>        (parameterize ([current-module-declare-name name])
> >>>          (eval `(,#'module any '#%kernel
> >>>                   (#%provide ,what)
> >>>                   (define-values (,what) #f))))
> >>>        (namespace-require `(for-template ,name))
> >>>        (namespace-syntax-introduce (datum->syntax #f what)))))
> >>>
> >>> This turns out to be a slightly slow part of the initialization of TR.
> >>> Does anyone know another way to get such an identifier?
> >>
> >>
> >> There's another way around this issue, which is to avoid creating these
> >> identifiers at all. In other words, change the representation of the
> type
> >> environment to something that supports symbol+module pairs as keys in
> >> addition to identifiers. The easiest way to do that is to add in a hash
> >> table behind the current free-id-table, since the two tables would
> handle
> >> disjoint sets of identifiers.
> >>
> >> Ryan
> >
> >
> > I would not have thought that'd work, but apparently identifier-binding
> will
> > give one that information.  Nice going, Ryan!
> >
> > --Carl
>
>
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