On 23/01/15 10:17, Simon Marlow wrote: > On 23/01/2015 04:12, Johan Tibell wrote: >> >> >> On Wed, Jan 21, 2015 at 5:48 PM, Simon Marlow <marlo...@gmail.com >> <mailto:marlo...@gmail.com>> wrote: >> >> On 21/01/2015 16:01, Johan Tibell wrote: >> >> My thoughts mostly mirror those of Adam and Edward. >> >> 1) I want something that is backwards compatible. >> >> >> Backwards compatible in what sense? Extension flags provide >> backwards compatibility, because you just don't turn on the >> extension until you want to use it. That's how all the other >> extensions work; most of them change syntax in some way or other >> that breaks existing code. >> >> >> In this case in the sense of avoiding splitting code into a new-Haskell >> vs old-Haskell. This means that existing records should work well (and >> ideally also get the improved name resolution when used in call sites >> that have the pragma enabled) in the new record system. > > I understand that position, but it does impose some pretty big > constraints, which may mean the design has to make some compromises. > It's probably not worth discussing this tradeoff until there's actually > a concrete proposal so that we can quantify how much old code would fail > to compile and the cost of any compromises.
In this spirit, I've started to prepare a concrete proposal for a revised OverloadedRecordFields design, based on recent feedback: https://ghc.haskell.org/trac/ghc/wiki/Records/OverloadedRecordFields/Redesign This would not necessarily include anonymous records at first, but they do fit nicely as a potential later extension, and it would work well with a slightly amended version of the record library in the meantime. I'd be very interested to hear what you think of this. Also, if someone would be prepared to flesh out a proposal based on the anonymous records idea, that might be a useful point of comparison. Adam -- Adam Gundry, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/ _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/mailman/listinfo/ghc-devs
