Analysis of the Scilab Language

Participants : Fabrice Le Fessant, Michael Laporte.

The Scilab language is a scripting language providing easy access to efficient implementations of mathematical operations (on matrices, for example). It suffers from the lack of verifications of an untyped language, together with the performance problems of an interpreted language. As part of the FUI Richelieu project, Fabrice Le Fessant and Michael Laporte have been investigating solutions to these issues.

The first part of the work was to clarify the semantics of the Scilab language. For that, an interpreter was implemented in OCaml, based on the C++ AST provided by the forthcoming version 6 of Scilab. This work exhibited a number of bugs in the new implementation, and proved to be more performant than the C++ implementation, thanks to a better algorithm to manage the dynamic scopes of Scilab.

The second part of the work was to understand how users write Scilab code. For that, a style-checking application, called Scilint, has been developed. It implements static checking of some properties of Scilab programs, to be able to detect runtime errors before running the program. Warnings are displayed for suspicious cases. Using Scilint on large sets of Scilab code (from the Scilab forge or the Atom repository) showed that the most erroneous features of Scilab are commonly used and that, to achieve the ultimate goal of partial typing of the language, a subset of the language must be specified that the user should conform to, in order for the code to benefit from the next part of the work, i.e. just-in-time compilation.