Github user afs commented on a diff in the pull request:
https://github.com/apache/jena/pull/337#discussion_r159528932
--- Diff: jena-base/src/main/java/org/apache/jena/atlas/lib/Pair.java ---
@@ -37,6 +40,30 @@
public A car() { return a ; }
public B cdr() { return b ; }
+ public static class OfSameType<T> extends Pair<T, T> {
+
--- End diff --
Point 3 was the observation
```
public <S, X> S apply(BiFunction<X, X, S> f, Function<T, X> op) {
return f.apply(op.apply(a), op.apply(b));
}
```
could be a function that can acts on `Pair<X,X>`.
```
static public <S, X> S apply(Pair<X,X> pair, BiFunction<X, X, S> f,
Function<T, X> op) {
return f.apply(op.apply(pair.car()), op.apply(pair.cdr()));
}
```
now whether `<S, X>` can meaningfully/usefully be `<S, X extends FOO>` and
interface FOO defines the "to boolean" method,
I don't usually push generics very hard - I leave that to Scala.
---
