State of the Scala 2 Union Adriaan Moors Scala Team Lead Scala - - PowerPoint PPT Presentation

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State of the Scala 2 Union Adriaan Moors Scala Team Lead Scala - - PowerPoint PPT Presentation

Jun 14, 2023 533 likes •1.03k views

State of the Scala 2 Union Adriaan Moors Scala Team Lead Scala 2.13 Developer survey! scala-lang.org/news/survey-2018.html Apache v2.0! scala-lang.org/news/license-change.html (deadline for any concerns: Aug 10) Library release

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State of the Scala 2 Union

Adriaan Moors Scala Team Lead

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Scala 2.13

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Developer survey!

scala-lang.org/news/survey-2018.html

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Apache v2.0!

scala-lang.org/news/license-change.html

(deadline for any concerns: Aug 10)

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Library release

scala/scala-dev#324

M4 out now M5 early August Final: October

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Headlines

Simpler collections Smaller core lib Faster compiler Java 9 support (minimal) User-friendliness

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Simpler Collections

Fix common gotchas Simplify implementation & usage Improved type inference of overloaded HO method Available now (M4)

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2.13.0-M4 upgrade

Thank you, ! × 18 scala/community-builds#710 @xuwei-k

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Smaller core lib

Parallel collections: ✅ compact1 profile: ✅ #6164 Make way for new modules #5677

Looking at you, scala.io, scala.sys

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Faster Compiler

Optimization Automated Benchmarking & Charting 20% improvement (last 12 months, hot compiler)

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User-friendliness

Improve tooling

Scala Center

Better docs

Great way to start contributing

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Scalafix

use for upgrade to 2.14 procedure syntax add sigs for implicits (& non-private members?) collections also, style checking / linting (built on scala.meta's semantic api)

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LSP: modern IDE support

Dotty presentation compiler TASTY and SemanticDB

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BSP / Build tools

Bloop (not a build tool) Mill (bazel-ish) Fury (source dependencies) <insert your build tool here>

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Typelevel & friends!

literal singleton types implicit search type constructor inference

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#help-wanted

Configurable error reporting Suppress warnings Nicer REPL

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Revamp REPL

syntax highlighting nicer editing cleaner wrapping improve embeddability (e.g. Spark) parity with Ammonite

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Intermezzo

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Scala?

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Fusion!

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Fusion ⇒ Flexibility

Powerful Also, challenging!

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OO & FP

  • bjects = modules

functions = small objects

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Safe & Concise

Static types: safety + understanding Type inference: elide details Together: refactoring

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Impure ↔ Pure Strict ↔ Lazy

Orthogonal concerns

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Scala Spectrum

Challenge: pick right point

(At least you have the choice.)

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GTD ↔ Correctness

Type checker = lightweight verifier Cost of Failure ↔ Verification?

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Cost of Abstraction

See: Why the free monad is not free

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Empathy-Driven Development

Math is good to recognize patterns But we need to communicate intent

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Math ↔ Practice

math / fun: inspires structure, not names modules: names, mutual recursion

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Future correctness checks?

Effect system? Ownership?

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Scala Spectrum

More opinionated in 3.0 Keep essential flexibility

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Scala 2.14

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Close the Scala 3 Gap

stdlib identical (2.13 & 3.0) TASTY interop shared compiler (post-typer) tooling

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T-AST-y?

Source code, fully type checked Full semantic information

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Binary Compatibility?

TASTY: Source compat == bin compat Not about: API evolution

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Simplify

github.com/scala/scala-dev/milestone/18

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Drop:

early initializers trait parameters procedure syntax

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Deprecate:

forSome: only wildcards value classes: opaque types whitebox macros: typelevel fun / codegen package object inheritance? vast implicit scope? (ignore packages in prefix)

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Add

trait parameters

  • paque types

type lambda

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Implicits

must have explicit return type lazy implicit (see: shapeless) multiple implicit parameter lists (see: Aux in shapeless)

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(Maybe) New JVM shiny

varhandles minimal value types? …

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Scala 3

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Kinda like 2.15

Just more exciting :-)

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Excitement

Implicit function types Union types transparent + principled meta-programming New macros enum @static

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Fin

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Grateful

Contributors Community Scala Center Dotty Team

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Thank you

Any Questions!?!