interace Foo { Object foo(int a, String b) };

Foo foo = aObjectWith#barSignatureMethod;
Foo foo2 = antherObjectWith#barSignatureMethod;

vs.

Object#(int a, String b) foo = aObjectWith#barSignatureMethod;
Object#(int a, String b) foo2 = aObjectWith#barSignatureMethod;

Of course we need somthing to convert between compatible single method intefaces as it would be possible with closures, like an extended type-cast:

interace Bar { String bar(int a, Object b) };

Foo foo = ..
Bar bar = (Foo as Bar) foo;