Template Haskell

Abstract: A wide range of domain-specific languages (DSLs) has been implemented successfully by embedding them in general purpose languages. This paper reviews embedding, and summarizes how two alternative techniques – staged interpreters and templates – can be used to overcome the limitations of embedding. Both techniques involve a form of generative programming. The paper reviews and compares three programming languages that have special support for generative programming. Two of these languages (MetaOCaml and Template Haskell) are research languages, while the third (C++) is already in wide industrial use. The paper identifies several dimensions that can serve as a basis for comparing generative languages.

Abstract: This paper explores the recent addition to Agda enabling reflection, in the style of Lisp and Template Haskell. It gives a brief introduction to using reflection, and details the complexities encountered when automating certain proofs with proof by reflection. It presents a library that can be used for automatically quoting a class of concrete Agda terms to a non-dependent, user-defined inductive data type, alleviating some of the burden a programmer faces when using reflection in a practical setting.

Abstract: Embedded domain specific languages (EDSLs) provide a specialised language for a particular application area while harnessing the infrastructure of an existing general purpose programming language. The reduction in implementation costs that results from this approach comes at a price: the EDSL often compiles to inefficient code since the host language’s compiler only optimises at the level of host language constructs. The paper presents an approach to solving this problem based on compile-time meta-programming which retains the simplicity of the embedded approach. We use PanTHeon, our implementation of an existing EDSL for image synthesis to demonstrate the benefits and drawbacks of this approach. Furthermore, we suggest potential improvements to Template Haskell, the meta-programming framework we are using, which would greatly improve its applicability to this kind of task.

Abstract: Compile-time meta-programming allows programs to be constructed by the user at compile-time. Although LISP derived languages have long had such facilities, few modern languages are capable of compile-time meta-programming, and of those that do many of the most powerful are statically typed functional languages. In this paper I present the dynamically typed object orientated language Converge which allows compile-time meta-programming in the spirit of Template Haskell. Converge demonstrates that integrating powerful, safe compile-time meta-programming features into a dynamic language requires few restrictions to the flexible development style facilitated by the paradigm. In this paper I detail Converge's compile-time meta-programming facilities, much of which is adapted from Template Haskell, contain several features new to the paradigm. Finally I explain how such a facility might be integrated into similar languages.