A typed intermediate language and algorithms for compiling scala by successive rewritings

Scala is a general-purpose programming language developed at EPFL. It combines concepts coming from object-oriented languages with other ones coming from functional languages. Scala is strongly typed and comes with a relatively complex type system, which incorporates several advanced concepts. The Scala compiler consists of successive phases, which rewrite the source code into ever simpler versions until the code is simple enough such that in can be trivially translated into object code. It is expected that each phase generates well-typed Scala code. This thesis starts by describing in details the main language constructions of Scala along with its type system. It then focuses on two rewriting phases whose implementation was much more difficult than expected. Indeed, during the development of the compiler, it was discovered that some programs cannot be simplified by rewriting them if the produced code has to be well-typed Scala code. The two problematic phases are described in details as well as the programs that cannot be correctly rewritten. A typed intermediate language that generalizes some aspects of Scala and thus enables the rewriting of all programs is described. The two rewriting phases are then formally described using this intermediate language

Inner Classes and Virtual Types

This paper studies the interplay between inner classes and virtual types. The combination of these two concepts can be observed in object-oriented languages like Beta or Scala. This study is based on a calculus of classes and objects composed of a very limited number of constructs. For example the calculus has neither methods nor class constructors. Instead it has a more general concept of abstract inheritance which lets a class extend an arbitrary object. Thanks to an interpretation of terms as types the calculus also unifies type fields and term fields. The main contribution of this work is to show that typing virtual types in the presence of inner classes requires some kind of alias analysis and to formalize this mechanism with a simple calculus

Pragmatic Type Interoperability

Providing type interoperability consists in ensuring that, even if written by different programmers, possibly in different languages and running on different platforms, types that are supposed to represent the same software module are indeed treated as one single type. This form of interoperability is crucial in modern distributed programming. We present a pragmatic approach to deal with type interoperability in a distributed system. Our approach is based on a specific serialization mechanism and a set of type conformance rules. We experiment the approach though .NET which we indirectly evaluate

An Overview of the Scala Programming Language

Scala fuses object-oriented and functional programming in a statically typed programming language. It is aimed at the construction of components and component systems. This paper gives an overview of the Scala language for readers who are familar with programming methods and programming language design

An Overview of the Scala Programming Language (2. Edition)

Scala fuses object-oriented and functional programming in a statically typed programming language. It is aimed at the construction of components and component systems. This paper gives an overview of the Scala language for readers who are familar with programming methods and programming language design

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Adding type constructor parameterization to Java

We present a generalization of Java’s parametric polymorphism that enables parameterization of classes and methods by type constructors, i.e., functions from types to types. Our extension is formalized as a calculus called FGJω. It is implemented in a prototype compiler and its type system is proven safe and decidable. We describe and motivate our extension through two examples: the definition of generic data-types with binary methods and the definition of generalized algebraic datatypes. The formalization and the safety and decidability proofs are, for space reasons, only shortly described