Minimally invasive interpreter construction: How to reuse a compiler to build an interpreter

Scripting languages are easy to use and very popular in various contexts. Their simplicity reduces a user's threshold of inhibitions to start programming - especially, if the user is not a computer science expert. As a consequence, our generative modeling framework Euclides for non-expert users is based on a JavaScript dialect. It consists of a JavaScript compiler including a front-end (lexer, parser, etc.) and back-ends for several platforms. In order to reduce our users' development times and for fast feedback, we integrated an interactive interpreter based on the already existing compiler. Instead of writing large proportions of new code, whose behavior has to be consistent with the already existing compiler, we used a minimally invasive solution, which allows us to reuse most parts of the compiler's front- and back-end