After more than a decade of research, visual languages have still not become everyday programming tools. On a
short term, an integration of visual languages with well-established (textual) programming languages may be more
likely to meet the actual requirements of pratical software development than the highly ambitious goal of creating
purely visual languages. In such an integration each paradigm can support the other where it is superior. We
propose a framework for heterogeneous languages, i.e., languages integrating visual and textual notation.
Particularly attractive is the use of visual expressions for the description of domain-specific data structures in
combination with textual notations for abstract control structures. In addition to the basic framework, we outline
the design of a development system that allows rapid prototyping of implementations of heterogeneous languages.
Examples will be presented from the domains of logical, functional, and procedural languages.