Scalawags #30: Live from Amsterdam

thescalawags's podcast

Scalawags #30: Live from Amsterdam

YouTube link: https://www.youtube.com/watch?v=atE_uKi-8so

Your hosts: Josh Suereth, Dick Wall, Heather Miller, Seth Tisue.

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

Intro (0:00)

• we're in beautiful, scenic Amsterdam for Scala Days, in a hotel room with the curtains drawn and the camera facing a blank wall
• it's the first day of Scala Days. so far we've only heard Martin's keynote, not any other talks

Martin's keynote (3:00)

• similar to Scala Days SF keynote
• heavy coverage of TASTY (Typed Abstract Syntax Trees -Yserialized)
• basic idea: JARs retain compiled Scala code in intermediate form (not only the bytecode), to permit on-the-fly rewriting and/or code generation. Scala 2 and Dotty could both target it
• macro definitions could run using a TASTY interpreter; then you wouldn't need two-stage compilation
• Scala.js got a shout-out from Martin

Macros in Scala 2.12 (12:00)

• the rumors are: blackbox macros are in, whitebox macros are out? (blackbox macros being "macros that faithfully follow their type signatures")
• blackbox macros are desirable because they don't defeat language tooling
• physical violence almost breaks out between Josh and Dick over kitten vs. puppy preferences

Typesafe name change (17:25)

• Dick is skeptical, but "I'm an engineer, not a marketer"
• Josh was skeptical at first; read his blog post, http://www.typesafe.com/blog/whats-in-a-name-typesafe-public-renaming-update-week-3
• Josh: "typesafe" means something to developers; to others, it isn't just meaningless, they can't even remember it
• Heather: it worked for Google
• Seth: oh hey by the way I work at Typesafe now (on the Scala team)
• Heather hotly denies membership in the Borg
• Typeface, oops Typesafe, and EPFL's relationship to Scala is discussed
• Seth: "When I hear the new name, I'll have an opinion then"
• Josh: "as long as it's a cool name"
• a round of astoundingly terrible name suggestions are made
• listeners think we're drunk. but define "drunk"

How do you tell people what your job is? (27:45)

• what is "Scala" anyway, to non-technical people? and how to explain why we like it so much?
• Dick: everyone's heard of Java, so tell them it's the new Java
• Java, that thing Windows wants me to update all the time
• Dick: tell them one or two actual problem domain you've worked on, e.g. genetics
• Josh: tell them Walmart, Twitter, LinkedIn
• Heather: "It's websites."
• Heather hotly denies doing websites
• Seth: but why do we like Scala so much?
• Heather: "Good design."
• Dick: "Power and flexibility."
• Josh: "Freedom without chaos."
• Seth: "It's more fun, but also safer."

Scala Library Improvement Process (37:55)

• PSA from Dick: new SLIP (Scala Library Improvement Process) is starting up. regular monthly meetings broadcast live. announcements, links, discussion at https://gitter.im/scala/slip
• Josh predicts this process will replace the SIP process
• Dick: we stole it from Rust

News roundup (44:10)

• Eugene Yokota has a new blog post series on Cats, similar to his well-known blog post series about Scalaz
  • http://eed3si9n.com/herding-cats/
• mandubian is blogging about Cats and free monads
  • http://mandubian.com/2015/04/09/freer/
• newly open sourced: Knobs, from the OnCue team at Verizon (Runar Bjarnason, Tim Perrett, et al). "A reasonable configuration library for Scala". Handles notifications to configuration changes, conveyed through Scalaz tasks
  • https://github.com/oncue/knobs
• from the same team, a logging library called Journal, based on SLF4J
  • https://github.com/oncue/journal
• Josh: logging should be structured events, not strings. strings bore Josh.
• Shapeless 2.2 is out
  • the automatic-derivation-of-typeclass-instances stuff that Miles Sabin presented at Scala Days SF, and discussed last episode, is in it
  • we didn't mention it in the podcast, but it now officially supports Scala.js
  • https://github.com/milessabin/shapeless/wiki/Release-notes:-shapeless-2.2.0
• Play 2.4 is out, with dependency injection replacing globals. behind the scenes it's Guice, but client code can interact with it in different modes

Annotations, macro and otherwise (53:50)

• Seth: Java annotations get out of hand and take over some styles of code, does anybody do that in Scala?
• Josh: not until we get annotation macros, then look out!
• Dick: annotations, Java's "get out of jail free" card
• Josh: "annotation macros are compile-time AspectJ"
• Heather sees Josh's dynamic-loading and dynamic-rewriting future and shivers
• Seth comes out swinging for annotation macros. it's wrong that something like case classes should be baked into the compiler
• Heather: well hmm, we did use annotation macros in a pickling prototype once

More news (1:01:15)

• new release of Doobie, Rob Norris (aka tpolecat)'s monadic database library
  • https://github.com/tpolecat/doobie
• all database API's are monadic now, monads won
• another day, another library by Haoyi Li: FastParse, fast parser combinators. now with more mutant cat eyebrows
  • claimed to be faster than stdlib parser combinators, easier to use than Parboiled 2
  • Seth wants to know if Haoyi's FastParse-based Scala grammar is the basis for the syntax highlighting in scalajs-fiddle and/or Ammonite? maybe not
  • http://lihaoyi.github.io/fastparse/
• Bill Venners won the 2015 Phil Bagwell Award
  • http://www.scala-lang.org/news/2015/06/25/bagwell-award-2015.html

Conclusion (1:10:50)

• jazz hands