In this tutorial participants learn how to build their own parallel programming language features by developing them as language extensions in the ableC [4] extensible C compiler framework. By implementing new parallel programming abstractions as language extensions one can build on an existing host language and thus avoid re-implementing common language features such as the type checking and code generation of arithmetic expressions and control flow statements. Using ableC, one can build expressive language features that fit seamlessly into the C11 host language.

This paper reformulates type qualifiers as language extensions that can be automatically and reliably composed. Type qualifiers annotate type expressions to introduce new subtyping relations and are powerful enough to detect many kinds of errors. Type qualifiers, as illustrated in our ableC extensible language framework for C, can introduce rich forms of concrete syntax, can generate dynamic checks on data when static checks are infeasible or not appropriate, and inject code that affects the program's behavior, for example for conversions of data or logging.

This paper describes an extensible language framework, ableC, that allows programmers to import new, domain-specific, independently-developed language features into their programming language, in this case C. Most importantly, this framework ensures that the language extensions will automatically compose to form a working translator that does not terminate abnormally. This is possible due to two modular analyses that extension developers can apply to their language extension to check its composability. Specifically, these ensure that the composed concrete syntax specification is non-ambiguous and the composed attribute grammar specifying the semantics is well-defined. This assurance and the expressiveness of the supported extensions is a distinguishing characteristic of the approach. The paper describes a number of techniques for specifying a host language, in this case C at the C11 standard, to make it more amenable to language extension. These include techniques that make additional extensions pass these modular analyses, refactorings of the host language to support a wider range of extensions, and the addition of semantic extension points to support, for example, operator overloading and non-local code transformations.