@postmodern
I'm really only familiar with having #mixins provide #compartmentef or #hierarchical #functionality, not actual #interfaces with Things.

Which is why I prefer #𝚔𝚒𝚗𝚍_𝚘𝚏? over #𝚒𝚜_𝚊? since a descendant of #String might be more than a string, although still having String's semantics.

E.g., in my game framework, a pouch, a desk, a location, and a room all mix in my Container module. Room is a kind of Location, but both have Container semantics.