Use looser callable type in place of Closure

[tyteen4a03]

Would it be possible for Collection methods to typehint for callable instead of Closure so I can pass non-anonymous functions to the methods?

[greg0ire]

Have you considered using Closure::fromCallable()?

[tyteen4a03]

Yes that's possible, but why not use a looser and 100% compatible type? AFAICT the code does not use characteristics only available to Closures.

[greg0ire]

Duplicate of #231

(and also, with first-class callable syntax, which creates closures, this is even simpler now than what I previously suggested)

[derrabus]

I've laid out my reasons for requiring closures here: #321 (comment)