I have a few generic `Map`s of String->Predicat...

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[Joe]

I have a few generic `Map`s of String->Predicate functions of different types. eg, a Map<String, (Int)->Boolean> and a Map<String, (String)->Boolean>. I'd like to combine them to get a Map<String, (Any)->Boolean>, but can't quite figure out how to do so safely. I can safely cast to Map<String, *> or Map<String, Any?> without an unchecked cast warning, but I can't safely cast to `Map<String, (*)->Boolean>`(compile error) or Map<String, (Any?)->Boolean> (unchecked cast)

[Joe]

ok, but how is it ok to cast to Map<String, Any?> ?

[robstoll]

One approach which is safe is to store the type of the parameter along with the function. You would get Map<String, Pair<KClass<*>, (Any) -> Boolean>> and you would need to apply the check for the parameter based on the KClass during runtime to stay safe.

[Joe]

The approach I've taken is to move the generics into an encapsulating class that can handle it, and have the outer class layers deal mostly with non-generic types when having to do so "across" the type grain. For example, a PredicateGenerator<T> that takes a <T> value in its constructor args, but exposes a getPredicate() that returns T/F based on the constructor args. Then I can, for example, AND a bunch of those together without having to know about the "inner" generic instance.