Hi, Milinda. I'll try to explain my reasoning of the situation. I always
find it helpful to macroexpand if I'm having trouble:
;; original version
user=> (macroexpand-1 '(ffff boby))
(clojure.tools.macro/macrolet [(defpop [] tu1282)] ;; <- undef. lookup
(clojure.core/defn user/execute [tu1282] boby))
;; Konrad's version
user=> (macroexpand-1 '(ffff-kh body))
(clojure.tools.macro/macrolet [(defpop [] (quote tu__1294__auto__))] ;; <-
(clojure.core/defn user/execute [tu__1294__auto__] body))
So, I think what is happening here is that the 'defpop' macro defined by
macrolet needs to return a piece of code (like all macros). Konrad's
version returns a symbol, so that's fine.
But the original version is trying to look up the piece of code stored in
the var tu1282 and return it. But that variable doesn't exist, so you get
the CompilerException. Here is a slight modification of your original that
explicitly does what Konrad did with auto-gensyms:
(defmacro ffff3 [body]
(let [x (gensym 'tu)
defpop-decl (list 'defpop [] (list 'quote x))] ;; <- return the
quoted symbol, no lookup
`(macrolet [~defpop-decl]
(defn execute [~x] ~body))))
Hope that helps,
Leif
On Wednesday, March 5, 2014 12:37:24 PM UTC-5, milinda wrote:
>
> Thanks Konrad. Your unquoting trick worked. But I am not exactly sure how
> to reason about these types of situations. Can you please shed some lights
> behind the logic of above unquoting if possible.
>
> Thanks
> Milinda
>
> On Wednesday, March 5, 2014 8:33:03 AM UTC-5, Konrad Hinsen wrote:
>>
>> --On 4 Mar 2014 23:07:27 -0800 milinda <milinda....@gmail.com> wrote:
>>
>> > I wanted macro to work like following.
>> >
>> >
>> > (ffff (let [x 10] (+ x (defpop))))
>> >
>> >
>> > This should generate function like
>> >
>> >
>> > (defn execute [tu3455] (let [x 10] (+ x tu3455)))
>>
>> Try this:
>>
>> (defmacro ffff [body]
>> `(macrolet [(~'defpop [] 'tu#)] (defn execute [tu#] ~body)))
>>
>> In action:
>>
>> user=> (macroexpand-1 '(ffff (let [x 10] (+ x (defpop)))))
>> (clojure.tools.macro/macrolet [(defpop [] (quote tu__818__auto__))]
>> (clojure.core/defn user/execute [tu__818__auto__] (let [x 10] (+ x
>> (defpop)))))
>>
>> user=> (macroexpand '(ffff (let [x 10] (+ x (defpop)))))
>> (do (def user/execute (fn* ([tu__818__auto__] (let* [x 10] (+ x
>> tu__818__auto__))))))
>>
>>
>> Konrad.
>>
>>
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