Ralf Lammel wrote:
Cédric Paternotte wrote:
...
> 5. With this :
http://www.cs.utexas.edu/ftp/pub/techreports/tr01-60/tr01-60.pdf
>
Gracjan Polak wrote:
I've been thinking about slight generalization of this lately. Here are
my semi-backed thoughts as of now.
I should have mentioned
http://homepages.cwi.nl/~ralf/OOHaskell/src/PoorMens2/
(again *not* using OOHaskell)
From the quick skim of code:
.?. -- apply function to upcast object
.!. -- apply modification function to upcast object and substitute
returned value (new object), basically update
Is there any description avaliable what is PoorMens2 all about?
A more general and preliminary observation:
the entire approach is potentially more about
object *composition* (and perhaps delegation)
rather than inheritance. Many OO evangelists
consider inheritance as a concept that was used
too much in early OO times, while object composition
is often more appropriate and flexible. So one *might*
say that this approach does not encode a Java-inheritance
solution but it does an inheritance-to-object-composition
migration on the fly. So what Gracjan calls "Inherits"
(and I call subtyping or substitution) is perhaps more a
"delegates".
Yes, I agree with this statement. The OP question was: how to simulate
inheritance in Haskell? One of the answers: using delegation :)
Ralf
--
Gracjan
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