The logic of extends? is much simpler, so try that. IIRC it's something
like "extends? returns true if any method on the protocol is implemented by
x", "satisfies? returns true if all methods of a protocol are implemented
by x".
The docs don't seem to give much help here, so play with it in the repl a
bit.
Timothy
On Thu, Jan 22, 2015 at 6:14 PM, Michael Blume <blume.m...@gmail.com> wrote:
> (defprotocol my-protocol
> (foo [this]))
>
> (extend-protocol my-protocol
> clojure.lang.IPersistentMap
> (foo [this] "hello from map"))
>
> (criterium.core/quick-bench
> (satisfies? my-protocol {}))
>
> (criterium.core/quick-bench
> (foo {}))
>
> Simply calling foo on an empty map takes 7 ns,
> but checking whether the map satisfies my-protocol takes 22 µs, 3000 times
> longer.
>
> It seems like to call foo, some mechanism has to look up an implementation
> of my-protocol for maps -- how is it we can do that so quickly for a call
> and so slowly for satisfies?
>
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