Switch on several values

[Clément BOUDEREAU]

Hi Remi,

Thank you for your feedback, this is exactly what I wanted to do.

Here is a tennis kata I made using pattern matching only:
https://gist.github.com/cboudereau/1f3ea7acd6d6712746c6d9f0e258deff#file-tennis-rs-L50
https://gist.github.com/cboudereau/ff891382a345ca81e8f4c6c836d9837b

You can also match higher tuple cardinality.

regards

On Wed, Sep 27, 2023 at 4:04 PM Remi Forax <forax at univ-mlv.fr> wrote:

> Hi recently Clément BOUDEREAU has reported a bug on amber-dev and
> unrelated to that bug,
> taking a look to the code I've noticed this
>
>
>        int compareTo(final Value<T> o) {
>             return switch (new Tuple<>(this, o)) {
>                 case Tuple<Value<T>, Value<T>>(Value.Infinite<T> _,
> Value.Infinite<T> _) -> 0;
>                 case Tuple<Value<T>, Value<T>>(Value.Infinite<T> _,
> Value.Fixed<T> _) -> 1;
>                 case Tuple<Value<T>, Value<T>>(Value.Fixed<T> _,
> Value.Infinite<T> _) -> -1;
>                 case Tuple<Value<T>, Value<T>>(Value.Fixed<T> fst,
> Value.Fixed<T> snd) ->
>                     fst.value.compareTo(snd.value);
>             };
>         }
>
> Here what Clément want is to match two values (here, "this" and "o") but
> the only way to do that is to wrap them into a pair (here named Tuple),
> Should we not provide a way to match several values natively ?
>
> Something like
>
>         int compareTo(final Value<T> o) {
>             return switch (this, o) {
>                 case (Value.Infinite<T> _, Value.Infinite<T> _) -> 0;
>                 case (Value.Infinite<T> _, Value.Fixed<T> _) -> 1;
>                 case (Value.Fixed<T> _, Value.Infinite<T> _) -> -1;
>                 case (Value.Fixed<T> fst, Value.Fixed<T> snd) ->
>                     fst.value.compareTo(snd.value);
>             };
>         }
>
> regards,
> Rémi
>


-- 
C.BOUDEREAU
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