Casting Metals - Speaker Deck

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CASTING METALS GABRIELE PETRONELLA

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CASTING METALS I’M GABRIELE ▸ Co-founder and Software Engineer at buildo ▸ Co-organizer of ScalaItaly ▸ Metals contributor

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CASTING METALS AGENDA ▸ Pre-Metals age ▸ Metals age ▸ …and beyond? Metals rich code editing for Scala in VS Code Vim Emacs By Ólafur Páll Geirsson https://www.youtube.com/watch?v=MRQMylDxBJ8

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QUICK SURVEY

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PRE-METALS AGE

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CASTING METALS 2013 - PROJECT KEPLER ▸ aka macros for Scala ▸ Landed in Scala 2.10 together with scala.reﬂect ▸ Authored by Eugene Burmako at EPFL

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CASTING METALS 2014 - PROJECT PALLADIUM ▸ ok, macros are great… ▸ …but can be also made easier to use? ▸ You may also know Project Palladium as Scalameta (at the time, scala.meta, for assonance with scala.reﬂect)

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CASTING METALS 2014 - SCALAMETA ▸ Announced publicly in 2014 at ScalaDays by Eugene Burmako (“Rethinking Scala Macros”) ▸ Intended as a principled foundation for meta programming, intended for use in a new macro system

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IT DIDN’T Narrator CASTING METALS

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CASTING METALS 2015 - SCALAMETA SYNTACTIC API ▸ By 2015, Scalameta syntactic API was ready for prime-time ▸ What is the syntactic API? ▸ Parser ▸ Data structures (Trees, Tokens) ▸ Pretty printer

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CASTING METALS 2016 - SCALAFMT ▸ Code formatter for Scala, based on Scalameta ▸ Developed by Ólafur Páll Geirsson, as his master thesis at EPFL ▸ Presented at Scala Italy 2016, in Venice!

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CASTING METALS 2016 - SCALAMETA SEMANTIC API ▸ The compiler knows a lot about your code ▸ Scalameta injects itself into the compiler, and it persists information about your code ▸ The information can then be re-used later on by external tools ▸ The data structure holding the information is known as Semanticdb ▸ See the very comprehensive spec https://scalameta.org/docs/semanticdb/ speciﬁcation.html

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TYPER BYTECODE SEMANTICDB

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CASTING METALS 2016 - MIGRATE4S SCALAFIX ▸ The idea: ▸ Scalafmt can fmt your code ▸ Scalafix can fix it ▸ Born in response to the goal of “to define a migration path from Scala 2.x to Dotty”, which came up in the first Scala Center Advisory Board meeting ▸ Authored by Ólafur, who’s at the time was a software engineer at the Scala Center

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CASTING METALS NOVEMBER 2017 - SCALA.IO ▸ I had just given a presentation about Scalaﬁx ▸ Scalaﬁx can now migrate your code, but also warn about unwanted patterns ▸ It would be neat to have that in your editor! ▸ But how?

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CASTING METALS IDE IDE FEATURES EDITOR

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SERVER CASTING METALS CLIENT / SERVER CLIENT FEATURES EDITOR ?

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SERVER CASTING METALS CLIENT / SERVER CLIENT FEATURES EDITOR LSP

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CASTING METALS 2016 - LANGUAGE SERVER PROTOCOL ▸ A standardisation effort made by Microsoft, in partnership with RedHat and Codenvy ▸ Created in the context of Visual Studio Code and open sourced on June 27, 2016 ▸ Extensible and “negotiable” ▸ You can implement only part of it, client and server negotiate the supported features ▸ You can extend it with custom features

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CASTING METALS BACK TO NOVEMBER 2017

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CASTING METALS BACK TO NOVEMBER 2017

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METALS AGE

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CASTING METALS JANUARY 14, 2018 - NAMING IS HARD

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CASTING METALS 2018 - POC PHASE ▸ Try doing everything! ▸ Entirely based on contributors’ free time ▸ It totally worked! Except for when it didn’t… ▸ “released” as 0.1.0

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rm -rf v0.1.0 v0.3.0 v0.4.0 v0.5.0 v0.6.0 v0.7.0

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CASTING METALS DECEMBER 7, 2018 - METALS 0.3.0 ▸ Build import ▸ Goto deﬁnition ▸ Accurate diagnostics

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CASTING METALS 2017 - BLOOP ▸ Build server around Zinc, the Scala incremental compiler ▸ Other build tools can integrate with it ▸ Developed at the Scala Center by Jorge Vicente Cantero (in photo) and Martin Duhem

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CASTING METALS 2018 - BSP ▸ Equivalent to LSP, but applied to build servers ▸ Joint effort of the Scala Center and the IntelliJ Scala team (Justin Kaeser, in photo)

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CASTING METALS BSP LSP

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CASTING METALS JANUARY 24, 2019 - METALS 0.4.0 ▸ Find references ▸ Find symbols in workspace ▸ Symbol outline ▸ Formatting

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CASTING METALS APRIL 12, 2019 - METALS 0.5.0 ▸ Completions ▸ Hover (aka type at point) ▸ Signature help (aka parameter hints) ▸ Code folding ▸ Document highlights

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CASTING METALS JUNE 11, 2019 - METALS 0.6.0 ▸ Build import for Maven, Gradle and Mill

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CASTING METALS JUNE 28, 2019 - METALS 0.7.0 ▸ Tree view ▸ Project explorer ▸ Libraries explorer ▸ Compilation explorer

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CASTING METALS SOON (LIKELY 0.8.0) ▸ Debugging support ▸ Pants integration ▸ Find implementations

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…WHAT NOW?

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CASTING METALS SCALA 3 + METALS = ▸ semanticdb-scalac compiler can be replaced by TASTY ▸ Dotty presentation compiler is developed with tooling in mind

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I WILL PERSONALLY WORK WITH OTHER PEOPLE ON THE DOTTY TEAM, WITH SCALA CENTER AND WITH VIRTUSLABS TO INTEGRATE METALS WITH TASTY AND THE DOTTY PRESENTATION COMPILER Martin Odersky - September 13, 2019 CASTING METALS