RTL also has constructions for expressing type checking, conversion, and selection in ways that are close to the semantics of Icon. Functions and operations written in RTL look substantially different from their former C versions, especially in their headers. However, most of the actual code is the same or similar to that for earlier versions. Some aspects of data representation and the way parts of the run-time system work are new with Version 9. These changes are summarized in the next section.
Several documents are be useful in understanding the implementation of Icon.
The information that follows assumes a basic knowledge of the implementation of Icon and the terminology used in it. The organization of the files for the implementation of Icon and its related components has changed in Version 9. Selection As mentioned above, RTL contains constructions for dealing with Icon type checking, conversion, and selection. The code for these operations is cast differently than before. Some descriptors in Version 9 are different from earlier implementations.