haberg at math.su.se
Tue Apr 8 10:00:46 EDT 2008
On 8 Apr 2008, at 15:26, PR Stanley wrote:
> I'm sure you could introduce change gradually without too much pain.
So then you only have to get the compilers to gradually understand
> I personally think "deriving" is a descriptive term, now that I
> understand its role better.
There are two processes here: deriving, i.e., inheriting an
interface; and instantiating, i.e., producing running code. Haskell
denotes derivation by "=>". And "data <a> deriving (b_1, ..., b_k)"
is really a short for
instance b_1 where <compiler implementation>
instance b_k where <compiler implementation>
So "instance" seems the word that should have been used.
But discussions of a change seems is likely just a café thing - I
must go finishing mine :-).
> I suppose you could consider "specialize" or "instanciate" but both
> those terms are very closely associated with OO and deriving an
> instance of a class with a type isn't quite like instantiation or
> even specialisation.
So then you introduce a new keyword and screwing up all existing code.
> We want a single word which is equivalent to "derives from".
> Deriving by itself can seem a bit ambiguous at first.
What about the already used "=>"?
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