Zach Tellman writes:
> I guess I'm confused, then. You contrast "complete recursive
> expansion" with what the compiler does, and then say it's recursive
> prewalk expansion, which is exactly what the compiler does. Can
> you clarify the difference between what you're doing and what the
> compiler does?
Here's an example:
(defmacro foo [x]
`(list ~x ~x))
(defmacro bar [x]
`[~x ~x])
Now let's work on the form
(foo (bar 'baz))
Plain macroexpand returns
(list (bar 'baz) (bar 'baz))
whereas tools.macro/mexpand-all gives
(list ['baz 'baz] ['baz 'baz])
It does this by first calling macroexpand, so foo gets called exactly
as during Clojure compilation and returns
(list (bar 'baz) (bar 'baz))
mexpand-all then goes through that form and expands the two subforms
(bar 'baz).
So mexpand-all does exactly what the compiler does, in particular it
calls the macros with exactly the same arguments. But the compiler
interleaves macro expansion with compilation, so it never gives you
access to the fully expanded but uncompiled form which is
(list ['baz 'baz] ['baz 'baz])
Konrad
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