[Haskell-cafe] Attempt to emulate subclasses in Haskell, am I reinventing the wheel?
Bardur Arantsson
spam at scientician.net
Mon Apr 20 18:26:01 UTC 2015
On 20-04-2015 20:01, Clinton Mead wrote:
> I've linked to an ugly attempt to emulate subclasses in Haskell, and I'm
> wondering if anyone has done what I have perhaps in a cleaner way.
>
Well, I would generally advise against trying to emulate a flawed
concept in the first place. "OverlappingInstances" and
"UndecidableInstances" are a red flag unless you know *exactly* what you
are doing.
A much better way (IMO, of course) is to use either
1) normal aggregation (that's the simpl{e,istic} answer), at
the cost of some boilerplate. If the boilerplate exceeds
practicality, I would look at
2) extensible records/row types as in e.g. "vinyl"
Regards,
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