A comprehensive introduction to type systems and programming languages. A type system
is a syntactic method for automatically checking the absence of certain erroneous behaviors …

We describe a design pattern for writing programs that traverse data structures built from rich
mutually-recursive data types. Such programs often have a great deal of" boilerplate" code …

Classical phantom types are datatypes in which type constraints are expressed using type
variables that do not appear in the datatype cases themselves. They can be used to embed …

Many important applications must run continuously and without interruption, yet must be
changed to fix bugs or upgrade functionality. No prior general-purpose methodology for …

A heterogeneous collection is a datatype that is capable of storing data of different types,
while providing operations for look-up, update, iteration, and others. There are various kinds …

We present the dynamically typed λ-calculus, an extension of the statically typed λ-calculus
with a special type Dyn and explicit dynamic type coercions corresponding to run-time type …

Find the type error in the following Haskell expression: if null xs then tail xs else xs You can't,
of course: this program is obviously nonsense unless you're a typechecker. The trouble is …

The polymorphic blame calculus integrates static typing, including universal types, with
dynamic typing. The primary challenge with this integration is preserving parametricity: even …

LNCS 2874 - The Klaim Project: Theory and Practice Page 1 The Klaim Project: Theory and
Practice * Lorenzo Bettini1, Viviana Bono2, Rocco De Nicola1, Gianluigi Ferrari3, Daniele …

We study an extension of gradual typing—a method to integrate dynamic typing and static
typing smoothly in a single language—to parametric polymorphism and its theoretical …