On Monday, 23 December 2013 at 03:45:07 UTC, Jakob Ovrum wrote:
We can't afford to add even more "tuple" types in library.
One tuple and two compile-time lists - where the auto-expanding
one covers the vast majority of use cases - doesn't sound at
all bad.
I think this is the root cause of disagreement and everything
else is just a consequence from it. I still remember my initial
confusion when trying to figure out this part of the language -
it wasn't really related to naming but more about trying to
understand what intended use cases does each entity have. It is
all natural once you start to casually use it but not before. If
both types are present in the library in the same time we will
need to explain why both are needed, what is the difference, when
each is expected to be used and so on. It is a serious risk of
cognitive overload considering one is already expected to get
some grasp about native template argument lists and how those can
be used. If there is only one type, it becomes considerably more
simple - just use it and once you get familiar with it deep
enough to need expansion behavior - `.expand` will be an expected
discovery.
Also having both types at the same time will cause difficulties
with template algorithms currently present in std.typetuple -
having some defined in terms of raw argument list and others in
terms of packed TemplateArgumentList is just another learning
curve damage.
What is even more important - auto-expanding lists simply don't
have any important value to preserve on their own as they are
already present in form of raw template arguments and `.expand`.
This was what made me change opinion on this topic back then.
