What's scala.js?

Transcript

1. What is Scala.js? Nov. 16, 2019 Kazuhisa Kawashima
2. Who am I • Name : Kazuhisa Kawashima • Home : Shizuoka shi, aoi ku • Company : YUMEMI inc. • Job : Computer Engineer • Favorite computer language : Scala, TypeScript
3. What is Yumemi? Company Features • We are a software engineering company. • We value the growth of everyone. • All employees are CEOs. • The salary is decided by yourself. • We decide all things by the proposal request. Reference : https://note.mu/raykataoka/n/n50c282bcb305
4. What is Scala.js?
5. Scala.js is ... • One of the AltJS • Create JavaScript from code written in Scala Scala JavaScript AltJS Scala.js TypeScript Kotlin.js CoffeeScript translate
6. Example code
7. Classes class Person { constructor(public firstName: string, public lastName: string) { } fullName() { return `${this.firstName} ${this.lastName}`; } } class Person(val firstName: String, val lastName: String) { def fullName(): String = s”${firstName} ${lastName}” } Scala.js TypeScript
8. Collections const personMap = new Map<number, Person>([ [10, new Person(“Roger”, ”Moore”)], [20, new Person(“James”, “Bond”)] ]); const names = new Array<string>(); for (const [key, person] of personMap) { if (key > 15) { names.push(`${key} = ${person.firstName}`); } } val personMap = Map( 10 -> Person(“Roger”, ”Moore”), 20 -> Person(“James”, “Bond”) ) val names = for { (key, person) <- personMap if key > 15 } yield s”$key = ${person.firstName}” Scala.js TypeScript
9. What can you do with Scala.js
10. On the node.js AWS Cloud Node.js npm module Scala.js AWS SDK for JavaScript
11. On the web browser Web browser Scala.js Storage Rest Client Framework(for instance, Vue.js) JavaScript / TypeScript View
12. What is Scala？
13. Scala is • Fusion of OOP and FP • Statically typed • Interaction with Java language • It takes longer to learn than other languages
14. Fusion of OOP and FP Object oriented language Procedures Data Functional language Side effects exclude fusion State exclude
15. Statically typed If you use Scala ... • The compiler check simple mistake before running. ◦ Missing a type ◦ Typo ◦ Missing number of arguments • You’ll be able to use the IDE effectivery ◦ Autocomplete ◦ Refactoring
16. • When you compile Scala code, it becomes a class file. • Scala PG run on the Java VM. Interaction with Java language Java VM Class file (Scala) Class file (Java) call Scala Class file compile
17. It takes time to learn longer... Monad Complex language specification Type class Implicit Functional It’s too difficult!
18. Don’t worry about it!
19. You can start to use Scala from better Java! val list = List(1, 2, 3, 4, 5, 6, 7, 8, 9) var sum = 0 list foreach(i => sum = sum + i) val list = List(1, 2, 3, 4, 5, 6, 7, 8, 9) val sum = list.foldLeft(0) {(s, i) => s + i} You can also use var! Let’s start to change var to val!
20. Scalapedia https://scalapedia.com/ プログラミング言語Scalaは、金融機関、クラウド事業者、広告配 信、モバイル・Webアプリケーションなどの業界で広く使われてい ます。 処理が高速で、かつ堅牢で安全なプログラムを構築できま す。 そのうえ、豊かな表現力によりコンパクトで保守性の高いプ ログラムを実現できるのが特徴です。 I’m writing an article in Scalapedia!
21. Scala Next
22. Loadmap • Now : version 2.13.1 • Scala 3 (Dotty) To be released in the fall of 2020 • Next : version 2.14 For easy migration to Scala 3
23. Finally We are hiring! Yumemi Recruit Information Welcome who want to work in Shizuoka with me! • Twitter : @cupperservice • E-mail : k_kawashima@yumemi.co.jp
24. Thank you for listening!