The de Bruijn principle and the compositional design of programming languages

Component-oriented development can be applied to programing languages themselves. The typical structure of languages’ semantic definitions using natural deduction rules lends itself to modularisation schemes in which the rules describing an individual language feature set may be composed freely with those of other feature sets without interference. We describe initial work on a system that encapsulates this approach to language design, which can generate language tools and their associated proof systems by composing descriptions of feature sets. The intention is to modularise the development and proof processes and encourage the population of an open set of interoperable and re-composable