Predicates?

[Brian Goetz]

> Predicate<String> isNull = Objects::isNull;
>
> On performance: I'm sure Guava is optimized so that its methods
> always return a singleton.  In principle, the semantics of lambdas
> and method references are abstract enough that you shouldn't have to
> worry about that.  In practice, I wouldn't expect clever
> optimizations like that (e.g., turning every "x -> true" into the
> same object) in the near future.

TO be clear: with our implementation, every invocation of the *statement*

   Predicate<String> p = () -> true;

always does return the same object.  What Dan is talking about is 
something different; if two places in the code have "equivalent" 
lambdas, whether they would be "interned".