17.06.19 17:47, Guido van Rossum пише:
Indeed it would work the same way as set comparison does, if you interpret a type as the set of its instances.
But I imagine that many Python users are not so familiar with this abstraction level (even if they use isinstance() and issubclass() all day long). Sometimes using a *different* operator is helpful to send a signal to the reader that a *different* kind of thing is being manipulated -- sort of like how you can tell that a collection is a list or a set by noticing whether values are added using append() or add().
Type theorists apparently have chosen to use the <: notation, and presumably for the same reason.
Then perhaps we should start to use <: for sets and left < and <= for types that support full ordering.