Hi, from all this I'm not so sure that these two techniques do not overlap. I mean HList tries to provide a technique for extensible Records, or composable data structures. So far it is possible in Haskell to extend / compose Data Structures but not at run-time and also rather clumsily. One could of course use tuples or rather nested pairs to compose data structures too, which would work at run-time. But that would be very hard to maintain. HList implements this composability by elaborate type-level programming. In my opinion functional references allows for this too but not through type-level programming. Am I wrong? Günther Am 04.02.10 13:18, schrieb Martijn van Steenbergen:
Edward Kmett wrote:
Functional references let you both read and write 'attributes' in a structure. These can be chained to access members of members.
You can also use them to build bidirectional views on fields (and compose those again as well).
Martijn.