no tag types

[Thomas Charles CONWAY]

I've talked with various Mercury people at different stages about
name-equivalence and no-tag types, eg:
	:- type foo ---> foo(int).
which, although less convenient than
	:- type foo == int.
avoids accidentally mixing foos and ints.

Maybe a useful thing would be to make:
	:- type foo = int.
be equivalent to
	:- type foo ---> foo(int).
except that it guarantees that foos will have the same runtime
representation as ints.

Expressions like:
	X = foo(42)
and
	X = foo(W), Z = foo(2 * W)
would mean excatly the same in both cases.

Comments? (Ie I've no idea how hard this would be to implement).

Thomas
-- 
Thomas Conway <conway at cs.mu.oz.au> )O+
To a killer whale, otters are like hairy popcorn -- Paul Dayton