Thank you, that really helps!
On Aug 4, 1:38 pm, Meikel Brandmeyer <m...@kotka.de> wrote:
> Hi,
>
> On Aug 4, 2:32 am, Yang Dong <ydong.pub...@gmail.com> wrote:
>
> > Thank you! I have just another question not related about this topic:
>
> > ;during bootstrap we don't have destructuring let, loop or fn, will
> > redefine later
> > (def
> > ^{:macro true
> > :added "1.0"}
> > let (fn* let [&form &env & decl] (cons 'let* decl)))
>
> > In Clojure 1.2.0, the preceding definition of let taks the strange
> > argument of `&form' and `&env'. What are they?
>
> user=> (defmacro foo [x y] (prn &form) (prn &env) `(+ ~x ~y))
> #'user/foo
> user=> (let [x 5] (foo x 6))
> (foo x 6)
> {x #<LocalBinding clojure.lang.compiler$localbind...@13f991>}
> 11
>
> &form contains the form how the macro was called. &env contains local
> bindings in the macro environment. (At least this is what my little
> test shows...) These magic parameters are given to all parameters, but
> usually hidden. It's probably safe to ignore them if you don't know
> what they really do.
>
> Sincerely
> Meikel
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