8.4 Compiled and Implementation-Specific Features

Often an implementation can implement an SLIB feature more efficiently than the R4RS-compliant source code in SLIB. Alternatively, implementations with compilers can compile SLIB source code into binary files which run faster than loading source code.

Additionally, the SLIB catalog can be augmented with extra-SLIB features which can be loaded by the implementation. The catalog format is described in See Library Catalogs.

These implementation-specific modifications are made when a new catalog is created (see Catalog Creation). If mkimpcat.scm in implementation-invicinity exists, it is loaded. That should produce the file implcat in implementation-invicinity, whose associations will override those of SLIB. implcat is copied into slibcat in implementation-vicinity as part of the catalog creation process; modifications to implcat after that will have no effect.