Scalawags #13

thescalawags's podcast

intro, intros (0:00)

• guest: Seth Tisue (Northwestern University). self-proclaimed "programming languages guy", Scala user since 2008, developer of NetLogo, a language for simulations and games

• http://ccl.northwestern.edu/netlogo/

• Dick is recovering from too much training and looking forward to the Java Posse Roundup 2014, a week of drinking and karaoke

• Feb 24-28 Crested Butte, Colorado

• http://www.mindviewinc.com/Conferences/JavaPosseRoundup/

• where is Daniel? Comcast ate his internet connection. he should move to Pittsburgh.

Northeast Scala Symposium 2014 (11:30)

• Mar 1-2 NYC

• http://nescala.org

• Seth: we found a bigger venue. pitchforks & torches have been put down.

• the talk schedule is posted. no more keynote slot. Daniel permanently defeats Josh 2-1, jerseys retired.

• big conferences are too much work to organize.

• Josh is working on sbt 1.0

• Dick secretly dresses up as Pokemon. Shhhhhhhh

uTest, Scala.js (12:35)

• https://github.com/lihaoyi/utest

• new testing library/framework by Haoyi Li. say it "micro test"

• 1000 lines of code. macro asserts give nice messages. sbt support.

• Scala.js compatibility

• macro for defining related tests that share setup, at multiple nested levels of sharing, lexically scoped.

• digression on Scala.js http://www.scala-js.org:

• can Scala.js integrate as nicely with the JS environment as regular Scala integrates with the JVM?

• if you need Google Closure do you lose separate compilation?

• code size, performance?

Slick 2.0 (34:20)

• Slick 2.0 has HLists for when you go past the 22 limit for tuples

• http://slick.typesafe.com

• in Scala 2.11 case classes will go past 22. but not tuples

• https://github.com/scala/scala/pull/2305 (Jason Zaugg)

Dotty (36:50)

• "Dependent Object Type Calculus"

• Dotty is now open source!

• https://github.com/lampepfl/dotty

• a viewer asks: "Does Dotty address any of Paul Phillips' concerns in its design?"

• compiler is "more functional" than current scalac, uses "aggressive caching" for performance

• Dotty type system is based on a calculus. But will type inference still go unspecified...?

• changes to how "lubs" (least upper bounds between types) are computed?

• does Dotty have a test suite yet? it better, soon!

• subscribe to new dotty-internals group if curious

• https://groups.google.com/forum/#!forum/dotty-internals

• what from Dotty will make it into mainline Scala someday? ideas? code?

• how free is Scala to change? it takes time to evolve the ecosystem and tooling. the example of Python 3 is a warning

• code coverage tools, do we use them?

• Dick is a consummate professional and thinks Dotty was named after his dog

ScalaCheck (51:20)

• http://www.scalacheck.org

• in practice, how useful is ScalaCheck, really? are we even allowed to question this?

• Dick has caught "maybe two or three errors" with it. "I'm just not sure the value proposition is there for me."

• Dick: "I would love to hear other people's experiences with ScalaCheck."

• Seth: "I've tried it a few times and haven't gotten a lot of value. But I want to believe."

• Josh used ScalaCheck to test a rule engine, successfully, and a parser, successfully.

• Combinatorics means random values might not include the interesting values.

• So you need to write the right generators. More work. Do you test your generator?

• viewer Michael Pilquist had success with using ScalaCheck to test scodec

• https://github.com/scodec/scodec

• one listener used ScalaCheck for XML stuff and didn't find anything but empty strings and MaxInt

• it's important to collect past failures and turn them into regular tests?

• did Dick just accuse ScalaCheck users of being too lazy to write regular tests? I think he kind of just did.

Esoteric Ecosystem Enumerated (1:10:20)

• there is a plugin for sbt that allows you to write Eclipse plugins using the Maven Tycho support for Eclipse

• https://github.com/ashewring/sbt-tycho

• Josh: "I'm so glad somebody wrote this but... Scala, Eclipse, and Maven and sbt [together] has me terrified. I'm so glad someone else wrote that."

• Josh pledges a beer to the author of the plugin.

• Seth mistakenly insinuates that Daniel likes Groovy

ScalaCheck redux (1:15:10)

• we tag our tests as fast vs. slow, not integration vs. unit

• Dick: "Tell me why I'm wrong. Tell me what I'm missing. I'd love to hear it."

• we're starting a Save Daniel's Internet fund. send us your account numbers and passwords