scalawags-34.md

Scalawags #34: The Collections They Are(n’t?) A Changin’

YouTube link: https://www.youtube.com/watch?v=uTiiwszdksU

Your hosts: Josh Suereth, Dick Wall, Daniel Spiewak, Seth Tisue

Join us during and between episodes for web-based Scalawags chat on Gitter.

Intro (0:00)

• the real theme music returns (and where it came from)
  • because Matthew Farwell insisted
• Josh is live from the belly of the beast
• Dick is not a professional audio engineer; Seth is not a licensed film theorist
• Heather is on her second trip through the transmogrifier

Scala 2.12.0-M3 (5:35)

• announcement:
  • http://www.scala-lang.org/news/2.12.0-M3
• ongoing optimizer/inliner improvements
• new tab completion in the REPL (coming also in 2.11.8)
  • your move, Ammonite

Gitter room reorg (8:30)

• scala/scala is the new scala/scala/scala-user
  • https://gitter.im/scala/scala
• scala/contributors is the new scala/scala
  • https://gitter.im/scala/contributors
  • like scala-internals
• Daniel is menaced by a bear
• Brendan McAdams is tired of these monkey fighting Scalawags

SIPs and SLIPs (12:20)

• meeting notes from Aug and Sep:
  • http://www.scala-lang.org/blog/2015/08/25/minutes-from-aug-2015.html
  • http://www.scala-lang.org/blog/2015/10/07/minutes-from-sept-2015.html
• help get the word out that this is even happening
• how do people get Scala news, anyway? (14:00)
  • https://twitter.com/scala_lang
  • http://scalatimes.com
  • https://twitter.com/scala_jp
    • run it through a translator
• Dick could use some help with the SIPs and SLIPs stuff, volunteers?
  • Helena Edelson volunteers to automate it via sbt

Collections (20:45)

• Josh had proposed changes just to views
  • scala/slip#17
• Martin: not just views, let's do collections too
  • "Wanted: Strawman proposals for new collections architecture"
  • CFP and discussion at scala/scala3#818
  • much further discussion at https://groups.google.com/d/msg/scala-debate/Z1YH_0Hgu5A/yqhTddk6AQAJ
• how restricting are Martin's proposed restrictions on new designs?
  • Daniel: "really, really, really constraining"
• elapsed time before someone makes fun of BitSet: about 5 minutes
• how to handle Range?
• would a Java 8 style design, where you explicitly jump into view/stream land at the start and then explicitly jump out again at the end, be good enough?
• what proposals exist?
  • Martin has a concrete proposal meeting his own requirements
    • https://github.com/lampepfl/dotty/blob/master/src/strawman/collections/CollectionStrawMan1.scala
    • it's only 404 lines
  • Dmitry Petrashko has a variant of it
    • scala/scala3#819
  • and after we recorded, Daniel put a sketch out
    • https://gist.github.com/djspiewak/2ae2570c8856037a7738
  • among proposals existing before Martin's CFP:
    • Bill Venners presented a collections design at Scala World
      • http://www.slideshare.net/bvenners/collections-prettyslow
    • and of course there's Paul Phillips' 2014 "PSP" design
      • http://www.slideshare.net/extempore/a-scala-corrections-library
• what matters more: efficiency of individual operations, or whether fusing of multiple operations is supported?
• extensional vs. intensional sets
  • Daniel recommends an "absolutely relentlessly fantastic" talk by Jed Wesley-Smith
    • we have no idea what the URL is, but maybe by the time you read this we'll have figured it out; check https://twitter.com/morazow/status/652945111219871746

Abrupt conclusion (49:05)

• we'll surely return to the topic of collections in the next episode