Hi again --
First, let me thank all of you for you kind and instructive comments.
Kent: thanks for the explanation of the relationships between reader
and macro expansion.
Patrick & Meikel: thanks! Your solutions do produce almost what I
need; the idea is with
(tm a b)
I should get back
{:a a :b b}
Your solutions produce sth equivalent to {:a (eval a) :b (eval b)} in
this case.
So maybe I am trying sth here that I shouldn't be doing in the first
place, but the context of the code is as follows:
(defmacro mk-create [creator-name & args]
`(defn create [...@args]
(let [r# (fetch "records")
id# (get-id)]
(store "records"
(assoc r# id#
{:id id#
;; :a a :b b ... obtained from args goes here
})))))
So my question is: what is the idiomatic way of getting the desired
result?
Thanks again, I really appreciate all your responses.
Best regards,
Ingolf
On Sep 5, 2:18 pm, Kent <[email protected]> wrote:
> When clojure evaluates a piece of code it goes through several steps.
> First the reader takes the string representation of your code and
> turns it into the clojure data structures represented by your code.
> Those data structures are then sent to the compiler for compilation,
> including possible macro expansion.
>
> Your code contains {~@(mapcat (fn [x] (list (keyword x) x)) args)} in
> it. The {} characters instruct the reader that this is a literal
> map. The reader expects a literal map to have an even number of
> elements, which your code does not have. It has one element.
> Therefore the reader throws an out of bounds exception. The exception
> is being thrown by the reader (the bit that takes a string and turns
> it into clojure datastructures) BEFORE it ever gets to the point where
> it is trying to do a macro expansion.
>
> Note that {:a} by itself also throws an ArrayIndexOutOfBounds
> exception.
>
> K.
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