This does seem like a strict improvement over the status quo.

Users can then conditionally get access to count(Trailing|Leading)Zeros by refining the type information available to them using this combinator, which offers a bunch of bit twiddling usecases.

-Edward

On Tue, May 18, 2021 at 9:30 AM Zemyla <zemyla@gmail.com> wrote:

Every Bits instance has to know that whether it's a FiniteBits
instance as well, due to bitSizeMaybe. Therefore, it should also be
able to tell a program that it is in fact a FiniteBits instance. There
should be a function added to Data.Bits.Bits:

withFiniteBits :: Bits a => a -> (FiniteBits a => r) -> r -> r

The default should be withFiniteBits _ _ x = x, at least for the next
several versions. bitSizeMaybe can be defined as

bitSizeMaybe x = withFiniteBits x (Just (finiteBitSize x)) Nothing

once everyone is on board with properly defining the value.
_______________________________________________
Libraries mailing list
Libraries@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries