refine `Callable` attributes as if they were functions and vice versa

It’d be nice to be able to refine Callable attributes as if they were functions and vice versa. Things that I’d like to see working:

abstract class Foo()
{
    shared formal String(String) surround;
}

class Bar()
extends Foo()
{
    shared actual String surround(String str) => "\{RIGHT DOUBLE QUOTATION MARK}``str``\{LEFT DOUBLE QUOTATION MARK}";
}

abstract class Foo()
{
    shared formal String id(String str);
}

class Bar()
extends Foo()
{
    id = identity<String>;
    // or
    // shared formal String id = identity<String>;
}

abstract class Foo<T>()
{
    shared formal T member;
}

class Bar()
extends Foo<String(String)>()
{
    shared formal String member(String str) => "\"``string``\"";
}

A little harder to support:

abstract class Foo()
{
    shared formal String member(String str);
}

class Bar()
{
    shared formal String(String) member
    {
        if(random())
        {
            retrun(identity<String>);
        }
        else
        {
            return(function(String str) => str + "!!!");
        }
    }
}

Oops, wrong repo, I’ll migrate this issue to the new repo. Derp.

[lucaswerkmeister]

Shortcut refinement supports both directions already:

abstract class Foo()
{
    shared formal String(String) surround;
}

class Bar()
extends Foo()
{
    surround(String str) => "\{RIGHT DOUBLE QUOTATION MARK}``str``\{LEFT DOUBLE QUOTATION MARK}";
}

try online

abstract class Foo()
{
    shared formal String id(String str);
}

class Bar()
extends Foo()
{
    id = identity<String>;
}

try online

abstract class Foo<out T>()
{
    shared formal T member;
}

class Bar()
extends Foo<String(String)>()
{
    member(String str) => "\"``string``\"";
}

try online