“Concepts ” are an essential language feature needed to support generic programming in the large. Concepts allow for succinct expression of bounds on type parameters of generic algorithms, enable systematic organization of problem domain abstractions, and make generic algorithms easier to use. In this paper we formalize the design of a type system and semantics for concepts that is suitable for non-type-inferencing languages. Our design shares much in common with the type classes of Haskell, though our primary influence is from best practices in the C ++ community, where concepts are used to document type requirements for templates in generic libraries. The technical development in this paper defines an extension to System F and a type-directed translation from the extension back to System F. The translation is proved sound; the proof is written in the human readable but machine checkable Isar language and has been automatically verified by the Isabelle proof assistant. This document was generated directly from the Isar theory files using Isabelle’s support for literate proofs.

FPM (Frequent Pattern Mining) is a data mining paradigm to extract informative patterns from massive datasets. Researchers have developed numerous novel algorithms to extract these patterns. Unfortunately, the focus primarily has been on a small set of popular patterns (itemsets, sequences, trees and graphs) and no framework for integrating the FPM process has been attempted. In this paper we introduce DMTL, a generic pattern mining library which fuses theoretical concepts from formal concept analysis and generic programming. It provides a framework that allows mining a large spectrum of patterns. We express each pattern in terms of its relational properties. Describing patterns based on their properties results in a pattern concept hierarchy. This hierarchical model is implemented using principles from generic programming. In this paper, we describe our design considerations and the subsequent implementation. Some of the challenges faced in terms of language features have also been highlighted. Apart from using the library in its entirety, we believe that some of its components, such as isomorphism checking, can be used independently. These components can definitely enrich the existing functionality provided in some of the popular libraries such as the Boost Graph Library. 1.

Since the Standard Template Library (STL), generic libraries in C++ rely on concepts to precisely specify the requirements of generic algorithms (function templates) on their parameters (template arguments). Modifying the definition of a concept even slightly, can have a potentially large impact on the (interfaces of the) entire library. In particular the non-local effects of a change, however, make its impact difficult to determine by hand. In this paper we propose a conceptual change impact analysis (CCIA), which determines the impact of changes of the conceptual specification of a generic library. The analysis is organized in a pipe-and-filter manner, where the first stage finds any kind of impact, the second stage various specific kinds of impact. Both stages describe reachability algorithms, which operate on a conceptual dependence graph. In a case study, we apply CCIA to a new proposal for STL iterator concepts, which is under review by the C++ standardization committee. The analysis shows a number of unexpected incompatibilities and, for certain STL algorithms, a loss of genericity. 1.

We formalize the informal definition of C ++ concepts that is currently considered by the C ++ standardization committee for inclusion in the next version of the language. Our definition captures the basic semantics of separate type checking, where conceptconstrained templates are checked separately from their uses and comprises of three main parts: non-standard name lookup, type checking of constrained templates, and implementation binding in concept maps. The formalization reveals two possible problems in the informal definition: hiding of names is not respected and incompatible implementations can be bound to concept entities. Furthermore, our definition allows formulating intuitively correct code that is rejected by the informal specification. 1