Re: Proposal: Move primitive-Data.Primitive.Addr API into base

Ptr Word8 is not (just) a pointer to byte-addressable memory. It's specifically a pointer to something representing an 8-bit unsigned integer. If you use a Ptr Word8 for the address of a floating point value, then you are *wrong* (or doing something very weird, anyway). To quote the documentation, A value of type Ptr a represents a pointer to an object, or an array of objects, which may be marshalled to or from Haskell values of type a. On Thu, Oct 25, 2018, 11:23 PM Carter Schonwald wrote:

... when is a valid pointer not going to point at byte addressable memory on memory architectures ghc can support or target?

On Thu, Oct 25, 2018 at 8:27 PM Daniel Cartwright wrote:

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Now, one could argue that `Ptr ()` isn't a lie, it sort of reads like C's void pointer. But surely something like `Ptr Word8` is a lie, when it is not actually a Ptr to Word8 values.

On Thu, Oct 25, 2018 at 8:11 PM Daniel Cartwright wrote:

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yes, only the type and its instances should be moved as far as i'm aware.

Also, it's more than just base.

this Ptr is a lie: https://hackage.haskell.org/package/ghc-compact-0.1.0.0/docs/GHC-Compact-Ser... these Ptrs are lies: https://hackage.haskell.org/package/base-4.12.0.0/docs/GHC-IO-Handle.html in GHC.Stats, the foreign import "getRTSStats" has `Ptr () -> IO ()`, this Ptr () is also a lie

These are just off the top of my head, there are more

On Thu, Oct 25, 2018 at 6:46 PM Carter Schonwald < carter.schonwald@gmail.com> wrote:

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hrmm, what are the pieces of base that are using Ptr when they really should be using Addr? This would help me understand what would be made better in base :)

On Thu, Oct 25, 2018 at 6:19 PM David Feuer wrote:

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We shouldn't really need to move anything into base except Addr and its base instances.

On Oct 25, 2018 5:59 PM, "Carter Schonwald" < carter.schonwald@gmail.com> wrote:

Indeed. The monad transformer instances for primmonad need to live in primmonad OR transformers to avoid orphans.

Either way, unless transformers moves into base (unlikely), no way anything using prim monad will.

On Thu, Oct 25, 2018 at 3:34 PM Andrew Martin < andrew.thaddeus@gmail.com> wrote:

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I like the idea of moving the type Addr into base. But we cannot move the entire module since it has functions that talk about PrimMonad, and we definitely don't want to move that into base.

On Thu, Oct 25, 2018 at 11:25 AM Daniel Cartwright < chessai1996@gmail.com> wrote:

> Motivation: There are a lot of places in base where 'Ptr a' is used > in place of 'Addr', because in base there is no 'Addr', only 'Addr#'. The > problem lies in the fact that many of these uses of 'Ptr a' are lying; the > 'a' value is meaningless. Authors of functions therein have used things > like 'Ptr ()', 'Ptr Word8', 'Ptr a', but these types do not mean what they > say they mean - they're just Addr. There are probably other motivations for > this that I can't think of off the top of my head right now. > _______________________________________________ > Libraries mailing list > Libraries@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries >

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

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