Removing bitSize

newer
generalize type of Data.Set.unions...

David Feuer

11 Jul 2017 11 Jul '17

3:50 a.m.

The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call. If the function is added, it would look like this: bitSize :: FiniteBits a => a -> Int bitSize = finiteBitSize The biggest downside I see is that we might one day want to reuse the name for something with a better type, such as bitSize :: forall proxy a. FiniteBits a => proxy a -> Int bitSize _ = finiteBitSize (undefined :: a) or bitSize :: forall a. FiniteBits a => Tagged a Int bitSize = Tagged (finiteBitSize (undefined :: a)) or (with type applications) bitSize :: forall a. FiniteBits a => Int bitSize = finiteBitSize (undefined :: a) Thanks, David Feuer

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Ivan Lazar Miljenovic

11 Jul 11 Jul

4:51 a.m.

On 11 July 2017 at 13:50, David Feuer wrote:

...

The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call.

As it's already DEPRECATED, I think it should be removed for a release first (in case anyone is still using it to help drive home the change in behaviour) before any alternative with that name is added. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com

Henning Thielemann

1:38 p.m.

On Mon, 10 Jul 2017, David Feuer wrote:

...

The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call. If the function is added, it would look like this:

bitSize :: FiniteBits a => a -> Int bitSize = finiteBitSize

I'd like to have a solution that allows me to make my code compilable by many GHC versions. The top-level function with an almost identical signature seems to fit that requirement best. The solutions using Proxy, Tagged, and TypeApplication are nice, too, but since there are many sensible choices there might also be many functions like bitSizeProxy, bitSizeTagged, bitSizeTypeApp.

David Feuer

4 Feb 4 Feb

9:15 p.m.

Quite some time has passed since I first raised this question. There doesn't seem to have been much discussion, but we really need to do something! Just leaving bitSize as deprecated seems like the worst option. Does anyone else have anything to add? On Mon, Jul 10, 2017 at 11:50 PM, David Feuer wrote:

...

The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call. If the function is added, it would look like this:

bitSize :: FiniteBits a => a -> Int bitSize = finiteBitSize

The biggest downside I see is that we might one day want to reuse the name for something with a better type, such as

bitSize :: forall proxy a. FiniteBits a => proxy a -> Int bitSize _ = finiteBitSize (undefined :: a)

or

bitSize :: forall a. FiniteBits a => Tagged a Int bitSize = Tagged (finiteBitSize (undefined :: a))

or (with type applications)

bitSize :: forall a. FiniteBits a => Int bitSize = finiteBitSize (undefined :: a)

Thanks, David Feuer

Andrew Martin

9:38 p.m.

I'm in favor of removing it entirely. Making it an alias may help people who want to keep code compatible with base < 4.7, but it could also introduce some confusion. Some thoughts: - It doesn't help people who want to write a `Bits` instance for their data type. That will still require CPP. - People writing bit-type-polymorphic code will have to upgrade to FiniteBits when using newer base, which will force CPP for compatibility anyway. - People writing bit-type monomorphic code don't even need this function, since they can just write out the number of bits (except for with Int and Word, whose sizes vary by platform). On Sun, Feb 4, 2018 at 4:15 PM, David Feuer wrote:

...

Quite some time has passed since I first raised this question. There doesn't seem to have been much discussion, but we really need to do something! Just leaving bitSize as deprecated seems like the worst option. Does anyone else have anything to add?

On Mon, Jul 10, 2017 at 11:50 PM, David Feuer wrote:

...
The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call. If the function is added, it would look like this:

bitSize :: FiniteBits a => a -> Int bitSize = finiteBitSize

The biggest downside I see is that we might one day want to reuse the name for something with a better type, such as

bitSize :: forall proxy a. FiniteBits a => proxy a -> Int bitSize _ = finiteBitSize (undefined :: a)

or

bitSize :: forall a. FiniteBits a => Tagged a Int bitSize = Tagged (finiteBitSize (undefined :: a))

or (with type applications)

bitSize :: forall a. FiniteBits a => Int bitSize = finiteBitSize (undefined :: a)

Thanks, David Feuer

Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

-- -Andrew Thaddeus Martin

Edward Kmett

10:41 p.m.

New subject: [core libraries] Re: Removing bitSize

As ugly as it is, this function is still mentioned in the current Haskell 2010 Report, so users should have some reasonable expectation of finding it. When there is a new Haskell Report that drops it I'd say that is when we should finish its removal. -Edward Sent from my iPhone

...

On Feb 4, 2018, at 4:38 PM, Andrew Martin wrote:

I'm in favor of removing it entirely. Making it an alias may help people who want to keep code compatible with base < 4.7, but it could also introduce some confusion. Some thoughts:

- It doesn't help people who want to write a `Bits` instance for their data type. That will still require CPP. - People writing bit-type-polymorphic code will have to upgrade to FiniteBits when using newer base, which will force CPP for compatibility anyway. - People writing bit-type monomorphic code don't even need this function, since they can just write out the number of bits (except for with Int and Word, whose sizes vary by platform).

...
On Sun, Feb 4, 2018 at 4:15 PM, David Feuer wrote: Quite some time has passed since I first raised this question. There doesn't seem to have been much discussion, but we really need to do something! Just leaving bitSize as deprecated seems like the worst option. Does anyone else have anything to add?

On Mon, Jul 10, 2017 at 11:50 PM, David Feuer wrote:

...
The long-deprecated bitSize method of the Bits class is slated to be removed in base-4.11 (GHC 8.4). There is one remaining question: should we replace it with a *function* by that name with a FiniteBits constraint? I don't feel very strongly either way, but Ryan Scott seems in favor and Edward Kmett seems opposed. So it seems best to bring it to the libraries list and let the CLC make the call. If the function is added, it would look like this:

bitSize :: FiniteBits a => a -> Int bitSize = finiteBitSize

The biggest downside I see is that we might one day want to reuse the name for something with a better type, such as

bitSize :: forall proxy a. FiniteBits a => proxy a -> Int bitSize _ = finiteBitSize (undefined :: a)

or

bitSize :: forall a. FiniteBits a => Tagged a Int bitSize = Tagged (finiteBitSize (undefined :: a))

or (with type applications)

bitSize :: forall a. FiniteBits a => Int bitSize = finiteBitSize (undefined :: a)

Thanks, David Feuer

Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

-- -Andrew Thaddeus Martin -- You received this message because you are subscribed to the Google Groups "haskell-core-libraries" group. To unsubscribe from this group and stop receiving emails from it, send an email to haskell-core-libraries+unsubscribe@googlegroups.com. For more options, visit https://groups.google.com/d/optout.

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Andrew Martin
David Feuer
Edward Kmett
Henning Thielemann
Ivan Lazar Miljenovic