On 08/09/2015 09:31, Simon Peyton Jones wrote:
| How did you envisage implementing anonymous boxed sums? What is their | heap representation?*Exactly* like tuples; that is, we have a family of data type declarations: data (a|b) = (_|) a | (|_) b data (a|b|c) = (_||) a | (|_|) b | (||_) c ..etc.
I see, but then you can't have multiple fields, like ( (# Int,Bool #) |) You'd have to box the inner tuple too. Ok, I suppose. Cheers Simon
Simon | | One option is to use some kind of generic object with a dynamic number | of pointers and non-pointers, and one field for the tag. The layout | would need to be stored in the object. This isn't a particularly | efficient representation, though. Perhaps there could be a family of | smaller specialised versions for common sizes. | | Do we have a use case for the boxed version, or is it just for | consistency? | | Cheers | Simon | | | > Looks good to me! | > | > Simon | > | > *From:*Johan Tibell [mailto:johan.tib...@gmail.com] | > *Sent:* 01 September 2015 18:24 | > *To:* Simon Peyton Jones; Simon Marlow; Ryan Newton | > *Cc:* ghc-devs@haskell.org | > *Subject:* RFC: Unpacking sum types | > | > I have a draft design for unpacking sum types that I'd like some | > feedback on. In particular feedback both on: | > | > * the writing and clarity of the proposal and | > | > * the proposal itself. | > | > https://ghc.haskell.org/trac/ghc/wiki/UnpackedSumTypes | > | > -- Johan | >
_______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
