Quoth Greg Weber
Many of the built-in record proposals seem more ambitious (create a new record from an existing one, generalize in some other direction). More power or generalization could be very useful, but it can wait for later - Haskell's records are glaringly bad because they lack name-spacing.
I think one of the problems being faced with improving records is a false choice between a quick but hacky library desugaring or a major "Extensible" records built into the compiler. What I am proposing is that (unless someone proposes a great desugaring solution) we make it the immediate goal to have records built into the compiler, but done in the simplest (perhaps least "Extensible") way that just accomplishes name-spacing.
It's sure easy to imagine something like that happening, in principle, but ... are you saying that extensibility specifically has been a major issue? Could be, I haven't been paying so much attention. Wouldn't extensibility more or less come along with row polymorphism? I mean, my understanding of the term is that an expression that instantiates a particular record field, can incorporate a record lacking that field, which seems to me to be implicit in row polymorphism anyway. I would think row polymorphism is a must-have. If you're interested in looking at old, Haskell-related record systems, also see O'Haskell. Donn