~technomancy/fennel#176: 
nested quoting doesn't work as expected

For the context, I've been trying to write a macro that generates another macro, e.g. like this Common Lisp macro:

(defmacro maker (name id)
  `(defmacro ,(intern (format nil "MAKE-~s" name)
                      (package-name (symbol-package name)))
     (a b c)
     `(list :id ,,id :a ,a :b ,b :c ,c)))

It can be used like this (maker foo 42) which produces a macro make-foo which in turn creates an object with baked-in ID from the parent macro, and supplied args:

* (macroexpand-1 '(maker foo 42))
(DEFMACRO MAKE-FOO (A B C) (LIST 'LIST :ID 42 :A A :B B :C C))
* (maker foo 42)
MAKE-FOO
* (make foo 3 7 11)
(:ID 42 :A 3 :B 7 :C 11)

However, when I try the same thing in Fennel, this happens:

>> (macro a [name id]
     `(macro ,(sym (.. :make- (tostring name)))
        [a b c]
        `{:id ,,id :a ,a :b ,b :c ,c}))
unknown:5:12 Compile error: tried to use unquote outside quote

     `{:id ,,id :a ,a :b ,b :c ,c}))
* Try moving the form to inside a quoted form.
* Try removing the comma.

It seems that nested quoting and multi-unquoting aren't supported, and all quoting operates on a single level. This isn't how quoting works in other lisps, such as Clojure, Racket, CL, and various Schemes.

Status
REPORTED
Submitter
~andreyorst
Assigned to
No-one
Submitted
11 months ago
Updated
11 months ago
Labels
bug

~technomancy 11 months ago

Yeah, I agree we should support this. I'm not sure when I'll have time to look into it.

~technomancy referenced this from #177 11 months ago

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