Yup, that solves it.
A while back the blah# didn't support working in nested back ticks. I
hadn't realized they fixed it. Or for that matter added condp :)
Thanks!
On Feb 5, 1:42 pm, Meikel Brandmeyer <m...@kotka.de> wrote:
> Hi,
>
> first things first: what you want to do is available as condp in
> the core library of Clojure. That said, here some things I
> noticed in your macro.
>
> You should not capture variables in your macros. That's bad style and
> might lead to clashes of names. Clojure provides the foo# notation
> to generate new symbols via gensym. This makes a call to gensym
> almost always unnecessary.
>
> Your pair-seq function may be written using the partition function
> from the seq-library: (pair-seq the-seq) <=> (partition 2 the-seq).
>
> One may specify a map between the argument vector and the docstring
> of functions and macros. This map becomes part of the metadata.
> Here this may be used to get some nice argument names in the
> doc output for the generated macro instead of the gensym names.
>
> Here we go:
>
> (defmacro def-casemacro [casename test]
> "Defines a macro named casename that uses test to compair the
> result of
> form to each key/result pair"
> `(defmacro ~casename
> ~(format "Evaluates form and finds the first key/result pair
> that %s is
> true for, evaluates it and returns the result. Error if none is
> found."
> (print-str test))
> {:arglists '([~'form ~'key-result-pairs])}
> [form# & key-result-pairs#]
> (let [key-gen# (gensym "key__")
> kr-pairs# (partition 2 key-result-pairs#)]
> `(let [~key-gen# ~form#]
> (cond
> ~@(mapcat (fn [[key# result#]]
> `((~'~test ~key-gen# ~key#) ~result#)) kr-
> pairs#)
> true
> (throw (new Error (format ~(str "No %s for key: %s")
> ~~(name casename)
> (str ~key-gen#)))))))))
>
> This works for me at least for the case (def-casemacro case =).
>
> Hope this helps.
>
> Sincerely
> Meikel
>
> smime.p7s
> 5KViewDownload
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