Bridging the tooling gap with Scala.js

me, hi!

stuff I do

Let's talk about JavaScript

'' == false // true [''] == '' // true [[]] == 0 // true typeof document.all // undefined document.all === undefined // false document.all === null // false document.all == null // true Number.MIN_VALUE > 0 // true ['1','2','3'].map(parseInt) // [1, NaN, NaN]

Built with JS desktop apps

Built with JS mobile apps

Built with JS backends

Oh, right, and the

It matters (like it or not)

A story

Mythical Trees and where to find them

AST Explorer

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First idea +-------------------------+ +------------------------+ | | | | | | | | | | | | | | source | | | +---------------------------------------> | | | | | | | | | | | | | | | AST EXPLORER | | JVM SERVER | | | | | | | AST | (SCALAMETA) | | | <---------------------------------------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-------------------------+ +------------------------+

downsides 4 loading time 4 extra infra

Write a parser from scratch

Scala.js?

Scala.js!

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Benefits 4 ! fast 4 ☁ no extra infra demo

Fast forward a few weeks

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First idea +-------------------------+ +------------------------+ | | | | | | | | | | | | | | source | | | +---------------------------------------> | | | | | | | | | | | | | | | VSCODE | | SCALAFMT CLI | | | | | | | formatted source | (JVM) | | | <---------------------------------------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +-------------------------+ +------------------------+

Downsides 4 ! slow (for a single file) 4 " not self-contained

Scala.js?

Yep

Upsides 4 ! fast 4 " self-contained Downsides 4 ! config -> cross-platform HOCON is still meh

Free ideas, grab them! 4 scalafmt on astexplorer.net 4 (alternatively) standalone playground on scalafmt.org 4 browser extension that formats code comments 4 scalafmt on scala native 4 GitHub app for scalafmt checks (talk to @laughedelic)

Thanks