Esterel Technologies

What is the difference between SCADE textual language and LUSTRE?

The textual SCADE language is what we often refer too as LUSTRE, but as explained below, there are differences between LUSTRE and textual SCADE and the correct name is thus SCADE textual language.

The actual textual SCADE language initially derives from the so-called V3+ version of LUSTRE, an industrial version that incorporates some extensions (like type refinements) with respect to LUSTRE V3. On the academic side, important extensions were added, to cope with a project of silicon compiling (in particular array types), and which gave birth to 2 other versions of the compiler: LUSTRE-V4 and LUSTRE-V5 (which are slightly different from the actual industrial version).

The textual SCADE language is used to save SCADE models. Therefore SCADE ".saofd" files contain the SCADE textual definition of their respective blocks (nodes, constants/types/global variables definitions). SCADE Editor enables to define a node directly with the SCADE textual language (textual nodes), which is handy for some low level nodes, typically library operators such as counters.

While SCADE language respects LUSTRE V3+ syntax and takes advantage of this language good properties, it also comes with several concepts such as genericity, assertions and annotations in order to meet the industry needs. The complete list of these added concepts is provided in the section Processing of the SCADE Concepts not Present in LUSTRE paragraph in chapter 2 of the Code Generator reference manual.

One of the slight differences between SCADE language and LUSTRE is the following: there is no ; character after the let keyword at the end of LUSTRE nodes, whereas there is one in SCADE textual language. There is no real reason for such syntactical difference, as it's just an historical one.

For further information about SCADE textual language, please refer to the SCADE Language reference manual. For further information about LUSTRE, please refer to the Verimag web page, at http://www-verimag.imag.fr/