[I replied on @cafe but didn't get any response. Trying again here.] Barney Hilken wrote:
What about just implementing the cheapest solution that still gets us most of the way?
(3) If it is as cheap (to implement) as advertised then there is no great risk involved. If it turns out the missing features are a great show-stopper for some people (which I don't believe) then let them present their case afterwards, with good examples at hand. We can still decide to aim for a higher goal in the long term.
If in doubt, chose the solution that is easier to implement.
Since this paper, there have been several proposals which can be 90% implemented as libraries, using either functional dependencies or associated types. These all have much more expressive type systems than the SPJ paper, yet need very little compiler support. The question is, which one (if any) should get this small but necessary support?
Could you be more specific? Which proposals exactly do you mean and where can I read more about them? (I know about HList/OOHaskell which is ingenious, of course, but not even the authors propose that a new Record System for Haskell should be based on their library, compiler support or no.) Cheers Ben