casting - How to cast to a type alias in Go?

Question

See this playground snippet.

Relevant code:

type somethingFuncy func(int) bool

func funcy(i int) bool {
    return i%2 == 0
}

var a interface{} = funcy

func main() {

    _ = a.(func(int) bool)  // Works

    fmt.Println("Awesome -- apparently, literally specifying the func signature works.")

    _ = a.(somethingFuncy)  // Panics

    fmt.Println("Darn -- doesn't get here. But somethingFuncy is the same signature as func(int) bool.")
}

The first cast works, by explicitly declaring the type. But the second cast panics. Why? Is there a clean way to cast to a longer func signature?

Answer 1

Waitting for answers