On Fri, Aug 14, 2020 at 7:51 AM Alexandre Almosni <
alexandre.almo...@gmail.com> wrote:
> Maybe your objects could be defined by a map containing functions and
> objects.
>
> So exampleAndList = {:fn and, :coll [a b c]}
>
>
> And then eval goes through your objects recursively, using
>
> (def eval [o]
> (apply (:fn o) (map eval (:coll o))))
>
> - with a special case that if o is not a map but say a Boolean you just
> return itself
>
A slight problem with that approach is that clojure.core/and is not a
function, but a macro: the reason being is that it stops evaluating forms
as soon as it hits a falsey value (similar for "or").
A smart implementation of And/OrList would like to short-circuit as well I
guess, so you'll need to express that somehow.
Of the clojure.core library that property is satisfied by transducers:
https://clojure.org/reference/transducers#_early_termination
Regards,
--
Alex
On 14 Aug 2020, at 02:24, Jack Park <jackp...@topicquests.org> wrote:
>
>
> The problem:
>
> In Java, I have an interface *IInferrable* which is basically boolean
> eval();
>
> Any Java object which extends IInferrable, no matter what it is, will
> answer to eval() and return a boolean.
> The idea lies at the heart of an inference engine.
>
> But, I also define a class *AndList* which implements IInferrable and
> extends java.util.ArrayList<Inferrable>
>
> So, AndList, and its sibling OrList behave just like a List object, but
> also will answer to eval() by running the collection and dealing with what
> each element returns when it, too, is eval()'d.
>
> I'd really love to discover how to pull that off in Clojure.
>
>
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