TROOPS - we are hiring talanted Scala engineers: https://troops.ai/careers Video: https://www.youtube.com/watch?v=dNyoPOyhYpg How does scalac compile implicit classes? Where does the implicit class get de-sugared and how is the implicit method represented inside the compiler? How does scalac search for a matching implicit method? Learn about the machinery behind the language semantics - the phases: parser, namer, typer and the data structures: Compilation Unit, Context, Tree, Symbol, Scope - by jumping into the code.

3. we’re hiring!
troops.ai/careers

4. Goal
Understand the Scala compiler by tracing the
compilation of a simple program and concentrating on a
single feature

5. Agenda
1. What is Implicit Conversion?
2. Result & RichResult
3. Compiler Data Structures & Phases
4. parser Phase
5. namer Phase
6. typer Phase

6. Implicit Conversion
1. Scala Language Specification 7.3
2. Scala Improvement Process 13
“In a selection e.m with e of type T, if the
selector m does not denote an accessible member of T
… a view v is searched which is applicable to e and
whose result contains a member named m.”
“An implicit class is desugared into a class and
implicit method pairing, where the implicit method
mimics the constructor of the class.”

7. Implicit Conversion
1. Scala Language Specification 7.3
2. Scala Improvement Process 13
“In a selection e.m with e of type T, if the
selector m does not denote an accessible member of T
… a view v is searched which is applicable to e and
whose result contains a member named m.”
“An implicit class is desugared into a class and
implicit method pairing, where the implicit method
mimics the constructor of the class.”

8. Result & RichResult

9. Result & RichResult

10. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

11. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

12. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

13. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

14. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

15. Data Structures
1. Compilation Unit
2. Context
3. Tree
4. Symbol
5. Type
6. Scope

16. Compiler Phases
1. parser
2. namer
3. typer

17. Compiler Phases
1. parser
2. namer
3. typer

18. Compiler Phases
1. parser
2. namer
3. typer

19. parser Phase

20. parser Phase
...

21. namer Phase

22. namer Phase - enterImplicitWrapper

23. typer Phase

24. typer Phase

25. typer Phase - Select

26. typer Phase - Select

27. typer Phase - View

28. typer Phase - View

29. typer Phase - View

30. typer Phase - View

31. The End

32. Thanks