These are chat archives for boostorg/hana
or.hppregarding forwarding of
hana::if_. It seems impossible unless you put the same logic that is in
hana::optional<T>or does one have to use
decltype(hana::just(std::declval<T>())? (the doc says "implementation defined" but I'm not sure to what extent)
hana::map< implementation_defined >but for optional it is
hana::optional<...>which makes me think it might be okay.
nothing’s type is
just(x)’s type is
hana::optional<>directly is okay?
I'm not sure if what I am doing is a good idea yet, but I decided to not bother wrapping
tuple and just represent a
message as a tuple where some 'fields' like a payload might not be present.
BOOST_HANA_CONSTANT_ASSERT( builder::entityMessages(entity_map, access_point) == hana::make_tuple( hana::type_c<hana::tuple< hana::optional<>, channel::Upstream, action::Create, path_type, hana::optional<entity::E1>, hana::optional<> >>, hana::type_c<hana::tuple< hana::optional<bool>, channel::Downstream, action::Create, path_type, hana::optional<entity::E1>, hana::optional<> >>, ) );
There is also this, but after a second look maybe I should have used
In any case it's nbd. I'll just avoid using it that way if it remains 'implementation_defined'.
value_orbecause I wanted that map lookup to be lazy
mpdef::Mapregistered at .5s for 200 lookups.
Your new post made me think of your todo in or.hpp regarding forwarding of x twice into hana::if_. It seems impossible unless you put the same logic that is in eval_if to convert x to bool or an IntegralConstant that contains bool.
That is correct, at least I think so. But I can't do that without losing the generality of
or_'s current definition, because someone could define a new
Logical that's not a
bool or a boolean
IntegralConstant. But even disregarding this issue, I feel like the
Logical concept might be flawed. I tried to be very general, but it gives something that provides bad compile-time performance for such basic operations. I would perhaps make more sense to only define these operations on boolean
IntegralConstants. We would lose the ability to branch on runtime values too, but the rest of the library does not support runtime conditions anymore anyways.
I didn't compare the benchmark against your version of the hash_map but the mpdef::Map registered at .5s for 200 lookups.
Care to send me the benchmark? Or did you already do it previously and I just forgot? I remember you showing me this graph before.
hana::mapis one deep freaking mystery. We made it better, but still not as good as we need for the most common use cases (types only or similar simple things).
optional, I’m thinking about it. The thing is that constructors are documented, so it would seem to make sense that the type part of the API too (otherwise how do you call the constructor?).
mpdefstuff my biggest speedup was using an empty list instead of
hana::tuple. It is almost exactly like
hana:typesonly it doesn't wrap its members in
hana::typewhen it returns them from e.g.
hana::tuplehas to have a bit of complexity to have an interface not too far from
hana::tupleis overload resolution on the constructors.
hana::typewould cause a significant compile-time hit, really.
detail::hash_table... maybe I should be using metafunctions
optional, I opened boostorg/hana#254 so I don’t forget it.