1. Designing a DSL in KOTLIN
@nicolas_frankel

2. Me, Myself and I By day By night Consultant Developer Blogger
Book author
Teacher/trainer
@nicolas_frankel #kotlin #dsl #kaadin

3. hybris, an SAP company
@nicolas_frankel #kotlin #dsl #kaadin

4. A DSL?
“A Domain-Specific Language is a computer language specialized to a particular application domain. This is in contrast to a General-Purpose Language, which is broadly applicable across domains.”
-- Wikipedia
@nicolas_frankel #kotlin #dsl #kaadin

5. GPL/DSL examples GPL DSL XML HTML MathML Java Hamcrest AssertJ
Fest Assert
Kotlin
Anko
Kaadin
Bean DSL
@nicolas_frankel #kotlin #dsl #kaadin

6. Designing a DSL in Java Method Sequencing Method Chaining
Nested Method Calls
Lambdas
@nicolas_frankel #kotlin #dsl #kaadin

7. AssertJ Sample
assertThat(frodo.getName()) .startsWith("Fro") .endsWith("do") .isEqualToIgnoringCase("frodo"); assertThat(fellowshipOfTheRing) .filteredOn(c -> c.getName().contains("o")) .containsOnly(aragorn, frodo, legolas) .extracting(c -> c.getRace().getName()) .contains("Hobbit", "Elf", "Man");
@nicolas_frankel #kotlin #dsl #kaadin

8. Kotlin
“Statically typed programming language for the JVM, Android and the browser” --
@nicolas_frankel #kotlin #dsl #kaadin

9. A few facts Developed by JetBrains Open Source Compiles to
Soon co-managed by Google
Open Source
Compiles to
JVM bytecode
JavaScript
(Native)
A "simpler Scala"
@nicolas_frankel #kotlin #dsl #kaadin

10. Kotlin features Functional and object-oriented Statically-typed
Null safe
No checked exceptions
Named & optional arguments
Lambdas
Extension functions
Java compatibility
(And more...)
@nicolas_frankel #kotlin #dsl #kaadin

11. Sample: Vaadin UI
public class SampleUI extends UI { @Override protected void init(VaadinRequest req) { setTheme("valo"); VerticalLayout layout = new VerticalLayout(); Label label = new Label("<strong>Hello</strong>", HTML); TextField field = new TextField("world!"); layout.addComponents(label, field); layout.setMargin(true); setContent(layout); } }
@nicolas_frankel #kotlin #dsl #kaadin

12. Our goal for DSL “Looks” declarative... But is code
@nicolas_frankel #kotlin #dsl #kaadin

13. Declarative Vaadin UI
class KaadinSampler : UI() { override fun init(req: VaadinRequest) { theme = "valo" verticalLayout(margin = true) { html("<strong>Hello</strong>") textField("world!") } } }
@nicolas_frankel #kotlin #dsl #kaadin

14. Demo!
@nicolas_frankel #kotlin #dsl #kaadin

15. Why not Groovy?
{ from to subject 'The pope has resigned!’ body { p 'Really, the pope has resigned!’ }
@nicolas_frankel #kotlin #dsl #kaadin

16. Why not Scala?
object SquareRoot extends Baysick { def main(args:Array[String]) = { 10 PRINT "Enter a number" 20 INPUT 'n 30 PRINT "Square root of " % "'n is " % SQRT('n) 40 END RUN }
@nicolas_frankel #kotlin #dsl #kaadin

17. Takeaways 100% Java interoperability Properties Extension Functions
Named parameters
Default values
Lambdas with receiver
(Operator overloading)
(Infix)
@nicolas_frankel #kotlin #dsl #kaadin

18. Q&A
@nicolas_frankel #kotlin #dsl #kaadin