[Haskell-cafe] functional references and HList?

Günther Schmidt gue.schmidt at web.de
Thu Feb 4 08:00:53 EST 2010


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?


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.

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