This document describes how to extend the [#!Gallesio93-1!#]
interpreter using the C language[#!Kernighan:CPL88!#]. To begin, we
will start with a simple extension which will only consist to add some
simple new primitives to the interpreter. Second section will describe
how to add a new type (and the primitives for manipulating this new
type). Another interesting extension consists to add new kind of
primitives (i.e. primitives which evaluate their argument in
particular way). This kind of extension will be discussed in the third
section. Fourth section discusses how to add a new widget to the
interpreter. Calling some Scheme code from a C function is showed in
section 5. And last, we will show how to load an extension at load
time. This facility will permit to extend the interpreter
without having to recompile it, on systems which support dynamic
loading.