Ross Paterson
On Wed, Mar 01, 2006 at 08:26:14AM +0000, Henrik Nilsson wrote:
I'm increasingly convinced that the records should be left alone for Haskell', possibly modulo some minor tweaks to polish the system.
Yes, no alternative candidate is available (specified, implemented, used).
Well, there _are_ some alternatives that have been specified and implemented e.g. TREX in Hugs, and experimental languages like Daan Leijen's Morrow. But the main reason I can see for there being little use of these candidates, is that they are not compatible with current Haskell. Thus, although I agree that none is ready for inclusion in Haskell-prime, I think we do need some mechanism for experimental records to be tried out in real Haskell implementations before the Haskell-double-prime committee starts its work. Perhaps, taking the extensions-layering idea, we could say that the current named-fields are encapsulated as an "extension that is part of the standard". Implementations could then introduce a flag to switch off this particular extension (current records) in conjunction with flags to switch on experimental replacements. This would give a certain flexibility for users to play with different systems, and the breaking of compatibility would be explicitly notated, either by the build options, or using a proposal like ticket #94. My suggestion is that we separate out everything from the Report to do with named-field records into something like a self-contained addendum. Whilst still an official part of the language standard, it might also be marked as a possibility for future removal. This would make it clear what parts of the language could be changed (or re-used without conflict) in an alternative records system. Regards, Malcolm