Is there any way one could define a method to accept both Functions and Functors?

General Usage
1

That is, without a Union. I still would like the function to be typed. So I don’t see

g(f, a) = let
     f(a)
end

as a solution (f should be typed).

2

Well, you can require that your functor types declare themselves as subtypes of Function (which is an abstract type that can be used as the parent of any type!).

Otherwise I don’t see how to avoid duck-typing. Any type can be made callable in Julia, so there is no way to identify callable objects by type in general.

2 Likes
3

See also: Is `Base.Callable` OK to use? Should it be documented? · Issue #43491 · JuliaLang/julia · GitHub

4

Good jumping off point, Stephen. Interesting discussion, that. Thank you.