Incremental concrete syntax for embedded languages with support for separate compilation

Embedded domain-specific languages (EDSLs) are known to improve the productivity of developers. However, for many domains no DSL implementation is available and two important reasons for this are: First, the effort to implement EDSLs that provide the domain's established syntax (called concrete syntax) is very high. Second, the EDSL and its underlying general-purpose programming language (GPL) are typically tightly integrated. This hampers reusability across different GPLs. Besides these implementation issues, the productivity gains of using EDSLs are also limited by the lack of explicit tool support for EDSL users such as syntax highlighting or code analyses. In this paper, we present an approach that significantly reduces the necessary effort to implement embedded DSLs with concrete syntax. The idea is to use island grammars to specify the EDSL's concrete syntax. This enables the developer to implement the embedded DSL as a library and to incrementally specify the concrete syntax using meta-data. Only those parts of the EDSL's grammar need to be specified that deviate from the grammar of the GPL. By analyzing an EDSL's implementation using reflection, it is possible to provide tool support for EDSLs without having the developer implement it explicitly, such as syntax highlighting. An evaluation demonstrates the feasibility of our approach by embedding a real-world DSL into a GPL. (C) 2012 Elsevier B.V. All rights reserved.