Question

A Predicate is just a Func which returns a boolean:

Predicate<T1, T2, T3, ...,Tn> = Func<T1, T2, T3, ...,Tn, bool> 

And an Action is just a Func which doesn’t return a value:

Action<T1, T2, T3, ...,Tn> = Func<T1, T2, T3, ...,Tn, void>

My question: Do Predicates or Actions have any additional properties or qualities which differentiate them to Funcs?

Answer 1

Nope. None whatsoever. They are all just delegate types. The only distinction is that some methods take things like Predicate<T> (mainly older APIs), and some take the Func<> / Action<>. One advantage of the Func<> / Action<> approach is that the signature is obvious from the name (i.e. a Func<int,float,string> takes an int and a float, and returns a string), but that’s it. And even if the delegates have the same signature, they are not directly interchangeable (you can’t pass a Func<T,bool> instance into a method that takes Predicate<T>).