Hi everyone, Ismael made a good point in the voting thread to expand the scope of this KIP to make functions covariant in their result types as well, so I did.
Please read the updated KIP https://cwiki.apache.org/confluence/display/KAFKA/KIP-100+-+Relax+Type+constraints+in+Kafka+Streams+API and the corresponding PR for the gory details https://github.com/apache/kafka/pull/2205 There were some subtleties related to functions applied to groupBy / aggregate methods due to differences in type inference between jdk 1.7 and 1.8. See the rejected alternatives section for an explanation of why the decision was made to go with invariant result types in those cases (for now). Let me know if you think everything makes sense. Xavier On Thu, Dec 8, 2016 at 10:35 AM Damian Guy <damian....@gmail.com> wrote: Hi Xavier, The KIP looks good - thanks! Damian On Thu, 8 Dec 2016 at 18:12 Xavier Léauté <xav...@confluent.io> wrote: > I recently filed https://issues.apache.org/jira/browse/KAFKA-4481, which > Guozhang agreed was a bug. However fixing this will require some minor > changes to the existing Kafka Streams APIs. > > I've outlined the required changes and binary / source compatibility > implications in the KIP > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-100+-+Relax+Type+constraints+in+Kafka+Streams+API > > Thank you, > Xavier >
