This paper describes a calculus for the stepwise and piecewise refinement of expressions. It provides a means for the derivation of executable expressions from initial specifications. We take the view that a refinement calculus consists of: a specification language, which usually includes constructs which are non-executable, but is a “superlanguage” of a programming language; a refinement relat...

In 1999, Richard Gordon, at that time Professor of Radiology at the University of Manitoba, Winnipeg, published a two-volume work under the ambitious title The Hierarchical Genome and Differentiation Waves: Novel Unification of Development, Genetics and Evolution. Eighteen years later, Gordon and his wife and former colleague Natalie present the differentiation waves theory to a broader public....

The paper “Scrap your Boilerplate” (SYB) introduces a combinator library for generic programming that offers generic traversals and queries. Classically, support for generic programming consists of two essential ingredients: a way to write type-indexed functions, and independently, a way to access the structure of data types. SYB seems to lack the second. As a consequence, it is difficult to co...