In some domains of programming it’s common to want to write a data structure or algorithm that can work with elements of many different types, such as a generic list or a sorting algorithm that only needs a comparison function.
Staapl is a collection of abstractions for metaprogramming microcontrollers from within PLT Scheme. The core of the system is a programmable code generator structured around a functional concatenative macro language adapted to a 2-stack machine model. On top of this it includes a syntax frontend for creating Forth style languages, a backend code generator for the Microchip PIC18 microcontroller architecture, and interaction tools for shortening the edit-compile-run cycle. It is structured as a code library to facilitate integration into larger systems employing a model-based design approach. The primary, practical goal is to provide a tool chain for programming low-end (8-bit) microcontrollers in a Forth-style language extended with powerful metaprogramming facilities. The secondary goal is to generalize and modularize this approach and extend it in two directions: to provide a standard machine model as an abstraction point for a large class of small embedded processo
"Generalized Algebraic Data Structures" have become a a hot new topic. They have recently been added to the GHC compiler. They support the construction, maintenance, and propagation of semantic properties of programs using powerful old ideas about types (the Curry-Howard Isomorphism) in surprisingly easy to understand new ways. The language Omega was designed and implemented to demonstrate their utility. Here a a few talks I gave that explains how they work. Also class lectures
for 6.10 We show how to build a quasiquoter for a simple mathematical expression language. Although the example is small, it demonstrates all aspects of building a quasiquoter. We do not mean to suggest that one gains much from a quasiquoter for such a small language relative to using abstract syntax directly except from a pedagogical point of view---this is just a tutorial!
An ingenious set of combinators for expressing pattern matching in a type-safe way. No ADTs required. Opens up the possibility of programming languages where we can declare new binding forms just as we declare new functions. abstract: Macros still have not made their way into typed higher-order programming languages such as Haskell and Standard ML. Therefore, to extend the expressiveness of Haskell or Standard ML gradually, one must express new linguistic features in terms of functions that fit within the static type systems of these languages. This is particularly challenging when introducing features that span across multiple types and that bind variables. We address this challenge by developing, in a step-by-step manner, mechanisms for encoding patterns and pattern matching in Haskell in a type-safe way.
c2005 Most new ideas in software developments are really new variations on old ideas. This article describes one of these, the growing idea of a class of tools that I call Language Workbenches - examples of which include Intentional Software, JetBrains's Meta Programming System, and Microsoft's Software Factories. These tools take an old style of development - which I call language oriented programming and use IDE tooling in a bid to make language oriented programming a viable approach. Although I'm not enough of a prognosticator to say whether they will succeed in their ambition, I do think that these tools are some of the most interesting things on the horizon of software development. Interesting enough to write this essay to try to explain, at least in outline, how they work and the main issues around their future usefulness.