The document discusses the use of Kotlin DSL for building domain-specific applications with various examples, including HTML creation and UI elements like forms and buttons. It also covers integration with Gradle for project management and demonstrates type-safe builders for object construction. Additionally, it explores features like extension properties and methods, and provides links to relevant GitHub repositories for further exploration.

1. Kotlin DSL
in under an hour
@antonarhipov

3. Yet

4. another
Yet

5. DSLanother
Yet

6. DSLanother
Yet
talk

7. Domain-specific, i.e.

8. tailored for the
specific task
Domain-specific, i.e.

9. External

10. External VS Internal

11. External VS Internal

12. External VS Internal

13. Internal

14. createHTML().html {
head {
+"Hello!"
}
body {
ul {
p {
+"This is my awesome text!"
}
}
}
}
kotlinx.html
https://github.com/Kotlin/kotlinx.html

15. Anko
https://github.com/Kotlin/anko
verticalLayout {
padding = dip(30)
val name = editText {
hint = "Name"
textSize = 24f
}
val pwd = editText {
hint = "Password"
textSize = 24f
}
button("Login") {
textSize = 26f
onClick { toast("Hello, ${name.text}!") }
}

16. Gradle Kotlin DSL
https://github.com/gradle/kotlin-dsl
plugins {
java
kotlin("jvm") version "1.2.70"
}
group = "org.arhan"
version = "1.0-SNAPSHOT"
repositories {
maven { setUrl("http://dl.bintray.com/kotlin/kotlin-eap") }
jcenter()
}
dependencies {
val kotlinx_html_version = "0.6.11"
compile(kotlin("stdlib-jdk8"))
compile("org.jetbrains.kotlinx:kotlinx-html-jvm:${kotlinx_html_version}")
testCompile("junit", "junit", "4.12")

17. Exposed
https://github.com/JetBrains/Exposed
object Cities : Table() {
val id = integer("id").autoIncrement().primaryKey() // Column<Int>
val name = varchar("name", 50) // Column<String>
}
transaction {
create (Cities)
val tallinnId = Cities.insert {
it[name] = "Tallinn"
} get Cities.id
for (city in Cities.selectAll()) {
println("${city[Cities.id]}: ${city[Cities.name]}")
}
}

18. https://github.com/nfrankel/kaadin
Kaadin
theme = "valo"
verticalLayout(margin = true, spacing = true) {
tabSheet {
tab("Interactions") {
accordion {
tab("Button", HAND_O_RIGHT) {
horizontalLayout(true, true) {
button()
button("Label")
button("Label", HAND_O_RIGHT)
button("Click me", onClick = { show("Clicked") })
button("Click me", HAND_O_RIGHT, { show("Clicked") })
}
}

19. k8s-kotlin-dsl
https://github.com/fkorotkov/k8s-kotlin-dsl
val client = DefaultKubernetesClient().inNamespace("default")
client.extensions().ingresses().createOrReplace(
newIngress {
metadata {
name = "example-ingress"
}
spec {
backend {
serviceName = "example-service"
servicePort = IntOrString(8080)
}
}
}
)

20. Kotlin DSL in TeamCity
project {
vcsRoot(ApplicationVcs)
buildType {
id("Application")
name = "Application"
vcs { root(ApplicationVcs) }
artifactRules = "target/*jar"
steps {
maven { goals = "clean package" }
}
triggers { vcs {} }
dependencies {
snapshot(Library) {}

21. fun main(args: Array<String>) {
embeddedServer(Jetty, commandLineEnvironment(args)).start(wait = true)
}
fun Application.main() {
install(DefaultHeaders)
install(CallLogging)
routing {
get("/") {
call.respondHtml {
head {
title { +"Ktor App" }
}
body {
p {
+"Hello from Ktor!"
}
}
Ktor

22. They all
look
similar

23. foo {
bar {
baz = "Hello!"
qux = quux {
corge = "Blah"
}
}
}

24. foo {
bar {
baz = "Hello!"
qux = quux {
corge = "Blah"
}
}
}

25. foo {
bar {
baz = "Hello!"
qux = quux {
corge = "Blah"
}
}
}

26. foo {
bar {
baz = "Hello!"
qux = quux {
corge = "Blah"
}
}
}

27. foo {
bar(grault = 1) {
baz = "Hello!"
qux = quux {
corge = "Blah"
}
}
}

28. foo {
bar(grault = 1) {
baz = "Hello!"
qux = quux {
corge = Blah()
}
}
}

29. foo {
bar(grault = 1) {
baz = "Hello!"
qux = quux {
corge = Blah()
}
}
}

30. foo {
bar(grault = 1) {
baz = "Hello!"
qux = quux {
corge = Blah()
}
}
}

31. Let’s write
some code!
https://github.com/jonnyzzz/kotlin-dsl-demo

32. Let’s write
some code!
https://github.com/jonnyzzz/kotlin-dsl-demo

33. Type-safe builders
https://kotlinlang.org/docs/reference/type-safe-builders.html

34. final ClientBuilder builder = new ClientBuilder();
builder.setFirstName("Anton");
builder.setLastName("Arhipov");
final TwitterBuilder twitterBuilder = new TwitterBuilder();
twitterBuilder.setHandle("@antonarhipov");
builder.setTwitter(twitterBuilder.build());
final CompanyBuilder companyBuilder = new CompanyBuilder();
companyBuilder.setName("JetBrains");
companyBuilder.setCity("Tallinn");
builder.setCompany(companyBuilder.build());
final Client client = builder.build();
System.out.println("Created client is: " + client);
val client = createClient {
firstName = "Anton"
lastName = "Arhipov"
twitter {
handle = "@antonarhipov"
}
company {
name = "JetBrains"
city = "Tallinn"
}
}
println("Created client is: " + client.consoleString)

35. //extension property
val Client.consoleString: String
get() = "${twitter.handle} ${company.name}"
//extension method
fun Client.toConsoleString(): String {
return "${twitter.handle} ${company.name}"
}

36. fun createClient(c: ClientBuilder.() -> Unit): Client {
val builder = ClientBuilder()
c(builder)
return builder.build()
}
fun ClientBuilder.company(t: CompanyBuilder.() -> Unit) {
company = CompanyBuilder().apply(t).build()
}
fun ClientBuilder.twitter(t: CompanyBuilder.() -> Unit) {
twitter = TwitterBuilder().apply(t).build()
}
Lambda with receiver
Extension methods

37. twitter {
handle = "@antonarhipov"
company {
name = "JetBrains"
city = "Tallinn"
}
}
@DslMarker
annotation class ClientDsl
@ClientDsl
class CompanyBuilderDsl : CompanyBuilder()
@ClientDsl
class TwitterBuilderDsl : TwitterBuilder()
twitter {
handle = "@antonarhipov"
company {
name = "JetBrains"
city = "Tallinn"
}
}
Scope control

38. Infix notation
https://kotlinlang.org/docs/reference/functions.html

39. dateTime = LocalDateTime.of(2018, Month.DECEMBER, 11, 0, 0)
dateTime = 11 December 2018 at (14 hh 0)
infix fun Int.December(n: Int) : LocalDate {
return LocalDate.of(n, Month.DECEMBER, this)
}
infix fun LocalDate.at(n: Pair<Int, Int>): LocalDateTime {
return this.atTime(n.first, n.second)
}
infix fun Int.hh(n: Int): Pair<Int, Int> {
return Pair(this, n)
}

40. T.() -> Unit

41. me {
name = "Anton Arhipov"
twitter = "@antonarhipov"
}
books { courses {
Kotlin {
Try = "try.kotlinlang.org"
Slack = "slack.kotl.in"
}