There's no such thing as a lazy map. into uses reduce, which is
necessarily not lazy either.
Clarity is in the eye of the beholder, of course. I think my version
is clearer, but if you replaced second/first with val/key I'd rate
them about the same. You might even replace (just val key) with
reverse - not sure if that's more readable, but there's certainly a
case for it.
On Sep 20, 9:52 am, John Cromartie <jcromar...@gmail.com> wrote:
> On Sep 20, 12:08 pm, Alan <a...@malloys.org> wrote:
>
>
>
> > A few days ago I was thinking about how different it would be to write
> > flip-map* in Java vs Clojure. A very simple, small program, but easy
> > to see how Clojure can be more expressive.
>
> > public static Map<V,K> flipMap(Map<K,V> map)
> > {
> > Map<V,K> result = new HashMap<V,K>(map.size());
> > for (K key : map.keys()) {
> > result.put(map.get(key), key);
> > }
>
> > return result;
>
> > }
>
> > (def flip-map #(apply zipmap ((juxt vals keys) %)))
>
> > * Given a hash map, reverse its keys and values such that every K=>V
> > pair in the input map becomes V=>K in the output. Naturally the values
> > must be unique for this to work, so call that a precondition.
>
> > On Sep 17, 2:47 pm, anderson_leite <anderson...@gmail.com> wrote:
>
> If I was going to write flip-map it might be a tad longer, but lazy
> and a bit clearer (IMO), with:
>
> (defn flip-map [m] (into {} (map (juxt second first) m)))
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