On Jul 29, 1:49 am, Sam Aaron <[email protected]> wrote:
> On 29 Jul 2011, at 07:22, Ken Wesson wrote:
>
> > On Fri, Jul 29, 2011 at 12:49 AM, Jeff Rose <[email protected]> wrote:
> >> I don't think it's very typical to pass a form to a function, unless
> >> you plan on using eval at runtime.
>
> > Or it's a function called by a macro to do some processing of forms.
>
> Yep, this is precisely what I was considering. I should have explicitly made
> mk-dynamically-bound-fn a macro in my example - a miscommunication on my part.
>
> On 29 Jul 2011, at 02:12, Alan Malloy wrote:
>
>
>
> > It's not clear how much of this is relevant to your actual problem, vs
> > the simple version you're posting here.
>
> Sorry, I was just trying to simplify things to try and get directly to the
> meat of the problem.
No apologies needed - reducing to a simple case is great. But here,
the simplification was probably too severe.
> > If you want something more general, that implicitly binds things for
> > you based on some code somewhere else (ew ew ew), then you need a
> > macro. This implementation is pretty gross; I suspect it could be
> > better, but you're trying to do something that seems weird to me.
>
> > (defn binding-vec []
> > ['size '(count args)])
>
> > (defmacro magic-fn
> > [& forms]
> > `(fn [& ~'args]
> > (let ~(binding-vec)
> > ~@forms)))
>
> > user> ((magic-fn (+ size 10)) 1 2)
> > 12
>
> Very cool, although it's not quite what I'd like. I'd like binding-vec to be
> a function of the resulting magic-fn's args.
>
> I'm aiming for something like this, but can't get it to quite work:
>
> (defn binding-vec [foos]
> '[size (count ~foos)])
>
> (defmacro magic-fn
> [& forms]
> `(fn [& ~'args]
> (let ~(binding-vec ~'args)
> ~@forms)))
>
> ((magic-fn (+ size 10)) 1 2) ;=> BOOM
(defn binding-vec [foos]
['size `(count ~foos)])
(defmacro magic-fn
[& forms]
(let [args (gensym 'args)]
`(fn [& ~args]
(let ~(binding-vec args)
~@forms))))
((magic-fn (+ size 10)) 1 2) ;=> 12
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