The compiler can figure out that the value of

   {1, 2, 3}

is a set containing the elements 1, 2 and 3.

The problem with the value of

    frozenset({1, 2, 3})

is that the value of frozenset depends on the context. This is because

    frozenset = print

is allowed.

According to help(repr):

    repr(obj, /)
        Return the canonical string representation of the object.
        For many object types, including most builtins, eval(repr(obj)) == obj.

Consistency suggests that if

    x = f{1, 2, 3}

gives always gives frozenset as the value of x then

    repr(x)

should be the string 'f{1, 2, 3}'. At present, I think, repr(x) always returns a literal if it can.

However, changing the repr of frozenset introduces problems of backwards compatibility, particularly in doctests and documentation.

Another way to achieve consistency is to make frozenset a keyword, in the same way that None, True and False are identifiers that are also language keywords.

Both proposals as stated have negative side-effects. I suggest we explore ways of reducing the above and any other side effects.

-- 

Jonathan