On 15/09/2011 15:43, Ian Lynagh wrote:
On Thu, Sep 15, 2011 at 08:47:30AM +0000, Simon Peyton-Jones wrote:
Provoked the (very constructive) Yesod blog post on "Limitations of Haskell", and the follow up discussion, I've started a wiki page to collect whatever ideas we have about the name spacing issue for record fields.
http://hackage.haskell.org/trac/ghc/wiki/Records
As Simon M said on Reddit, this is something we'd like to fix; but we need a consensus on how to fix it.
Re TypeDirectedNameResolution, I would actually prefer it if it were less general. i.e. if you were to write x.f then f would be required to be a record selector.
Then there's no need for the "If there is exactly one f whose type matches that of x" unpleasantness. Instead, the type of x must be inferred first (without any knowledge about the type of f), and then we know immediately which f is being referred to.
One benefit of TDNR is to replicate the discoverability of APIs that OO programming has - if x :: Foo then typing "x." in an IDE gives you a list of things you can do with a Foo. (Obviously it's not a complete lis for various reasons, but it does allow the author of Foo and others to design discoverable APIs.) So I think we'd be losing quite a bit to force f to be a record selector. Ganesh