On Mon, Oct 26, 2009 at 1:55 PM, Abhijith <abhiji...@gmail.com> wrote:
>
> Hello everyone,
> I am having problems with destructuring in doseq.
>
> The function below basically takes an array of arrays as its argument
> and returns a mapping of the elements to the index in the outer array.
>
> (use 'clojure.contrib.seq-utils)
> (defn foobar [arr--of-arr]
> (let [ acc (transient {}) ]
> (doseq [ [i e] (indexed arr-of-arr) word e ]
> (assoc! acc word (if-let [v (acc word)] (conj v i) [i])))
> (persistent! acc)))
[snip]
> Either that, or doseq is not meant to be used in the above fashion.
You nailed it. It's not about destructuring, it's using doseq to
"bash in place" a transient collection. You won't get correct
results unless you take the return value of 'assoc!' as your new
collection. Even though most of the time it will return the same
transient you passed in with your changes applied to it,
sometimes it returns a new transient. By using doseq you're
losing that returned transient and running into problems.
You could try using 'reduce' instead of 'doseq' -- I think that
will point you in the right direction.
BTW, your example args are vectors not arrays.
--Chouser
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