On 07/09/2015 15:35, Simon Peyton Jones wrote:
Good start.
I have updated the page to separate the source-language design (what the
programmer sees) from the implementation.
And I have included boxed sums as well – it would be deeply strange not
to do so.
How did you envisage implementing anonymous boxed sums? What is their
heap representation?
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
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