On Mar 30, 2:54 pm, Mark Engelberg <mark.engelb...@gmail.com> wrote:
> On Mon, Mar 30, 2009 at 10:45 AM, Mark Engelberg
>
> <mark.engelb...@gmail.com> wrote:
> > I don't know whether this fix would be worth the performance penalty,
> > though, but it's what would "feel right" to me.
>
> If it's not practical to always reduce integers when used as keys,
> then I think it would be useful for a variation of
> clojure.lang.Numbers/reduce to be exposed as a common function in the
> API so that users can easily do their own reduction upon interop with
> Java, before storing in a hash-map or hash-set. Note that
> clojure.lang.Numbers/reduce does not accept a regular Integer as an
> input, so the API version should also cover that case, and just return
> the same Integer. I'm thinking num-reduce might be a good name.
> Maybe num-reduce could also convert float to double (doubles are what
> Clojure uses internally, right?). So basically, it would guarantee
> that your number is converted into Clojure's standard representation
> for that kind of thing so that it can be compared/hashed/etc. with
> Clojure's numeric computation results with no surprises.
>
> If something like this is not put in the API, I can add something like
> this to clojure.contrib.math, but it seems like it would be a
> generally valuable tool for numeric interop, and thus worthy of
> inclusion in the core.
contrib.math is a good first place for num-reduce, as all of
contrib.math will end up in core soon.
Towards that end, I wonder if someone would do some analysis of the
costs of contrib.math using multimethods vs e.g. the dispatching
techniques of clojure.lang.Numbers for some of the operations. Are
there places where the multimethod dispatch dominates the math? IMO
math ops are not necessarily the best place for the elegance of
multimethods, but, depending on the op, it might not matter.
Rich
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