Composable first-order predicate trait.
This library implements an interface to “predicates” - boolean-valued functions of one argument. This allows combinatorial logic to be created and assembled at runtime and then used one or more times for evaluating values. This sort of object is really useful when creating filters and checks that can be changed at runtime with user interaction - it allows a clean separation of concerns where the configuration code can be used to build up a predicate, and then that predicate can be given to the code that does the actual filtering without the filtering code knowing anything about user configuration. See the examples for how this can work.