Awesome. Thanks for the answers everyone. I'm probably going to end up doing a namespace-require on the arbitrary code within a new namespace and then use eval to test any macros within it.
Cody On Fri, Feb 1, 2013 at 7:29 AM, Ryan Culpepper <ry...@ccs.neu.edu> wrote: > The answer is roughly "that is not possible". In general, the meaning of a > macro cannot be represented by a run-time value (but see below), so if you > want to do something reflection-based with macros, you probably need to > change your design to deal with terms (represented by syntax objects) > instead of values. > > Actually, it does make sense to talk about the run-time value that > corresponds to a macro in the case of identifier macros---macros that can > be used like variables. For example, if you use 'contract-out' to provide a > variable 'f' with a contract, it actually creates an auxiliary identifier > macro and provides that as 'f'. The expansion of the provided 'f' macro > fills in the negative blame part of the contract with the module where the > expansion occurred and applies the contract to the original 'f' variable. > > That's the situation handled by the extension of 'dynamic-require' to > macros. So doing > > (dynamic-require mod macro-name) > > is approximately the same as > > (parameterize ((current-namespace (make-empty-base-namespace))) > (namespace-require mod) > (eval macro-name)) > > (except that it uses 'namespace-attach-module' instead of just > 'namespace-require'). If 'macro-name' happens to be a macro that acts like > a variable, then 'eval' produces a value. Otherwise, if it's something like > 'define' or 'match' or 'for/list', you get an error, and it's exactly the > same error you would get if you wrote something like > > #lang racket > for/list > > What to do next depends on what you want to do with the macros. > > Ryan > > > > On 02/01/2013 02:57 AM, Dan Grossman wrote: > >> >> Cody and I would love an answer to this question from 1.5 months ago if >> anybody can point us in the right direction and/or ask us to clarify the >> question. Or if the answer is "that is not possible" then we'll do >> something else. >> >> Much thanks! >> >> --Dan >> >> On Mon, Dec 17, 2012 at 9:20 PM, Cody Schroeder <codeblac...@gmail.com >> <mailto:codeblac...@gmail.com>**> wrote: >> >> I'm in a position that I would like to use dynamic-require >> <http://docs.racket-lang.org/**reference/Module_Names_and_** >> Loading.html#(def._((quote._~**23~25kernel)._dynamic-require)**)<http://docs.racket-lang.org/reference/Module_Names_and_Loading.html#(def._((quote._~23~25kernel)._dynamic-require))>> >> to >> >> gain access to all of the provides in a module. This is quite >> straightforward for normal procedures, but I also want this to >> include syntax. However, I get this error when trying to >> dynamically require the blah macro from my test module: >> >> (dynamic-require "test.rkt" 'blah) >> blah: use does not match pattern: (blah body) in: blah >> >> From the spec, it says that "If the module exports provided as >> syntax, then a use of the binding is expanded and evaluated in a >> fresh namespace to which the module is attached" when using >> dynamic-require. I don't understand how it's being used, though. >> >> Is there a way to use dynamic-require how I want? Is there a >> better way? >> Cody >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/**users<http://lists.racket-lang.org/users> >> >> >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/**users<http://lists.racket-lang.org/users> >> >> >
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