Paul Sandoz paul.sandoz at
Wed Jul 22 08:10:56 UTC 2015

On 20 Jul 2015, at 19:08, Remi Forax <forax at> wrote:

> Hi all, hi Paul,
> I've found that the signature of Stream.generate doesn't to use a wildcard hence some program are rejected even if there are valid, by example:
>  public static void main(String[] args) {
>      Supplier<String> supplier = () -> "hello";
>      Stream<CharSequence> s = Stream.generate(supplier);
>  }
> The fix is simple, in interface Stream, generate should be declared like this :
>  public static<T> Stream<T> generate(Supplier<? extends T> s)
> and
> the field 's' of the InfiniteSupplyingSpliterator.OfRef should be also declared as a Supplier<? extends T>.

I believe such changes to Stream.generate are backwards compatible because overriding is not possible. (In addition static method on an interface are scoped to that interface, but i am not sure if that matters in this case.)

We could also adjust Stream.iterate as well:

  public static<T, S extends T> Stream<T> iterate(final S seed, final UnaryOperator<S> f)

Seems appropriate for consistency with Stream.generate. I presume that is backwards compatible as well?


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