How Scala is made

Scala Days SF 2015 presentation on how we think of Scala as a product.

Transcript

1. How
 Scala
 is made Grzegorz Kossakowski
 Typesafe @gkossakowski
2. Plan • why do we make Scala • how do we go about new features • what practices and tools • who is making Scala
3. Impact
4. Popularity Novelty Small impact
5. Popularity Novelty Medium impact
6. Popularity Novelty Large impact
7. Popularity Novelty Stability Large impact
8. Stability understand loss aversion
9. Features & stability
10. Dumb down?
11. Making a feature • 12 months are needed to develop a new feature • feedback from existing projects is essential • good design is best achieved after couple of failed iterations
12. Releasing a feature Segment your audience. Make a feature an opt-in.
13. Feature flags Feature Flag Bytecode emitter -Ybackend Lambda translation -Ydelambdafy Functional interfaces -Xexperimental New optimizer -Yopt Lambda bytecode -target Classpath handling -YclasspathImpl
14. Tools are top priority http://algeri-wong.com/yishan/engineering-management- tools-are-top-priority.html
15. Scala ♥ GitHub
16. Shorten the feedback loop
17. Make change validation impersonal
18. Pull request validation
19. Dbuild: testing at large scale 1.5 million lines of Scala compiled every night 80+ community projects covered
20. Community build https://github.com/scala/community-builds
21. Bugs caught • Tricky (new) optimizer bugs that led to incorrect behaviour at runtime (#4312) • Edge cases in translation to Java 8-style lambdas • Tuple optimization in pattern matcher (#4376)
22. Reactive infrastructure
23. Reactive infrastructure
24. Resilient infrastructure Recovers cheaply & happily.
25. Resilient infrastructure • Infrastructure as Code (IaC) • Fully automated • Easy to manage • Easy to track changes
26. Crowd behind Scala
27. Crowd behind Scala 49% 43% 8% Community EPFL Typesafe Commits to 2.10
28. Crowd behind Scala 55% 23% 22% Community EPFL Typesafe Commits to 2.11 Almost 3x! More time for research
29. Crowd behind Scala 5 4 33 Community EPFL Typesafe 2.10 team size Almost 3x! More time for research Members submit 90% of all commits
30. Crowd behind Scala 5 4 47 Community EPFL Typesafe 2.11 team size +42% Members submit 90% of all commits
31. Crowd behind Scala commits 2.10 commits 2.11 team (90%) 2.10 team (90%) 2.11 everyone 2.10 everyone 2.11 community 8% 22% 33 47 69 104 epfl 43% 23% 4 4 19 13 typesafe 49% 54% 5 5 22 22 all 4495 2582 42 56 110 139
32. Recap • Making Scala is about impact • Stability & novelty • Tools are top priority • We’re proud that Scala is becoming increasingly open
33. Thank you! \_(ツ)_/¯ @gkossakowski