proposal: Go 2: functional interface like implementation

[mstrYoda]

Currently Go has first class functions and duck type interfaces.

It would be handy to have functional interfaces for easily passing a function as a parameter to another function that expects an interface with has only one function definition.

Example:

type Some interface {
  SomeFunc(param int) int
}

func Test(s Some) {
...
}

f := func(a int) int {
...
}

Test(f)

WDYT about it?

[fzipp]

This is a duplicate of #21670

[mstrYoda]

This is a duplicate of #21670

Thank you, closed.