COMPILING SCALA FOR THE JAVA VIRTUAL MACHINE - EPFL

Contents
1 Introduction 7
1.1 Scope ................................ 7
1.2 Background ............................ 8
1.2.1 The Scala programming language ........... 8
1.2.2 The Java virtual machine ................ 9
1.2.3 The Scala compiler .................... 10
1.3 Inheritance graph notation .................... 13
2 Mixins 15
2.1 Introduction ............................ 15
2.1.1 Single inheritance ..................... 15
2.1.2 Multiple inheritance ................... 15
2.1.3 Mixin inheritance ..................... 16
2.1.4 Trait inheritance ...................... 16
2.2 Mixin inheritance in Scala .................... 17
2.2.1 Mixin example ...................... 18
2.3 Encoding mixins on the JVM .................. 19
2.3.1 Typing aspect ....................... 20
2.3.2 Code sharing aspect ................... 20
2.3.3 Encoding used by scalac ................ 22
2.4 Interfaces for types ........................ 25
2.4.1 The AddInterfaces phase ................ 25
2.4.2 Unmixable classes .................... 26
2.4.3 Subclasses of Java classes ................ 27
2.4.4 Private members ..................... 28
2.5 Inlining mixin code ........................ 29
2.5.1 The ExpandMixins phase ................ 29
2.5.2 Mixin type parameters .................. 30
2.5.3 Mixin constructors .................... 30
2.5.4 Private members ..................... 31
2.5.5 Overridden members .................. 31