["python","hash","set"]
Why aren't Python sets hashable?

I stumbled across a blog post detailing how to implement a powerset function in Python. So I went about trying my own way of doing it, and discovered that Python apparently cannot have a set of sets, since set is not hashable. This is irksome, since the definition of a powerset is that it is a set of sets, and I wanted to implement it using actual set operations. >>> set([ set() ]) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unhashable type: 'set' Is there a good reason Python sets are not hashable?
Generally, only immutable objects are hashable in Python. The immutable variant of set() -- frozenset() -- is hashable.