On 18/01/2012, Gábor Lehel
(I *am*, however, uncomfortable with using straight-up type level strings, without consideration for any particular alternative. If nothing else they should at least be opaque symbols which can be passed around and used in the supported contexts but not manipulated as strings. String-based hackery should be left to Template Haskell, and out of the type system. I can't really express at the moment why in particular I think it would be bad, but it feels like it would be bad.)
I strongly agree; plus, it's awkward (and ugly) that a selector be desugarred to a type-level string of its key identifier, as if it were some perverse quasiliteral. The trouble is, if they were opaque, then how could a function be polymorphic over all records with a certain member, with defined semantics? How could one tell the compiler that the semantics of all such members are the same? One must define a name, and then the problem of namespace non-interoperability that is now a great bother would be a greater bother yet.