We are interested in the composition of languages, in particular a
data description language and a paradigm-specific language, from a
pragmatic point of view.
Roughly speaking our goal is the description of languages in a component-based style, focussing on the data definition component.
The proposed approach is to substitute the constructs dealing with
data from the "data" language for the constructs describing data
that are not specific to the particular paradigm of the
"paradigm-specific" language in a way that syntax, semantics as well
as methodologies of the two components are preserved.
We illustrate our proposal on a toy example: using the algebraic specification language CASL, as data language, and a "pre-post" condition logic à la Hoare, as the paradigm specific one.
A more interesting application of our technique is fully worked out in ReggioRepetto00b and the first step towards an application to UML, that is an analysis of UML from the data viewpoint, following the guidelines given here, is sketched at the end.
The postscript version of this paper is available through anonymous ftp at ftp.disi.unige.it, in /person/ReggioG/AstesianoEtAll00a.ps