That sort of works for my use case.
What I want to do is define a grammar...
(def num-graph
(graph
num ~(or ~succ ~zero)
succ (succ ^x ~num)
zero zero))
... attach actions ....
(def num-out
(output-in num-graph
'zero (fnk [] 0)
'succ (fnk [x] (inc x))))
... and compile the result ...
strucjure.regression.tests> (graph->view 'num num-out)
(clojure.core/letfn
[(num ...)
(succ ...)
(zero ...)]
(clojure.core/fn
[input__2288__auto__]
(num input__2288__auto__)))
This works fine as long as the fnks dont close over anything, but
that's very limiting.
If I eval that code and *then* wrap it in (binding ...) I can have
closures but that now means that I can't do call-site compilation.
I'll have to poke around a bit more...
On 28 August 2013 18:32, Aaron Cohen <[email protected]> wrote:
> I'm not sure if you'll consider this hacky or not.
>
> (def ^:dynamic *fn-helper*)
>
> (defn eval-at-one [f] (binding [*fn-helper* f] (eval '(*fn-helper* 1))))
>
>
> On Wed, Aug 28, 2013 at 1:28 PM, Jamie Brandon
> <[email protected]> wrote:
>>
>> You will also run into problems if your functions close over any data:
>>
>> user> (let [f (fn [] 1)] (eval `(~f)))
>> 1
>> nil
>> user> (let [x 1 f (fn [] x)] (eval `(~f)))
>> IllegalArgumentException No matching ctor found for class
>> user$eval38616$f__38617 clojure.lang.Reflector.invokeConstructor
>> (Reflector.java:163)
>>
>> I'm struggling with this as well, I'm definitely interested in finding
>> a non-hacky way to pass closures through eval without leaking memory.
>>
>> Perhaps something like:
>>
>> (let [x 1
>> f (fn [] x)
>> f-sym (gensym)]
>> (intern *ns* gensym (weak-ref f))
>> (with-meta (eval `(fn [] (do-stuff-with @~f))) {::strong-ref f}))
>>
>> So that way f will be freed up when the resulting fn is gced.
>>
>> On 28 August 2013 17:59, Ben Wolfson <[email protected]> wrote:
>> > On Wed, Aug 28, 2013 at 9:27 AM, Jamie Brandon
>> > <[email protected]> wrote:
>> >>
>> >>
>> >> If you aren't worried about leaking memory, a possible workaround is
>> >> to intern the fn in some namespace and then put the symbol in the
>> >> macro output.
>> >
>> >
>> > Hrm, I hope it doesn't come to that---as long as I'm creating the
>> > functions
>> > with their metadata, I can make things work, because I can add extra
>> > information to the with-meta call or do extra things when making the
>> > call.
>> > What I'd like, though, is for it to be possible to copy the metadata
>> > over to
>> > a new function by client code, just using the regular (with-meta (fn
>> > [blah]
>> > blah) (meta old-fn)) mechanism. But then the sneaky symbol, or whatever
>> > extra thing, in the metadata, that's used in the form to be eval-ed is
>> > pointing to the original function, not the one passed in. Maybe just
>> > providing a utility for fixing up the metadata is the right move, though
>> > it's kidn of dissatisfying.
>> >
>> >
>> > --
>> > Ben Wolfson
>> > "Human kind has used its intelligence to vary the flavour of drinks,
>> > which
>> > may be sweet, aromatic, fermented or spirit-based. ... Family and social
>> > life also offer numerous other occasions to consume drinks for
>> > pleasure."
>> > [Larousse, "Drink" entry]
>> >
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