Green Card ``connects'' with code in other modules in two ways:
Green Card reads the source code of any modules directly imported by
the Haskell module being processed. It extracts %dis function
definitions (only) from these modules. This provides an easy mechanism
for Green Card to import DIS functions defined elsewhere.
It is often important to arrange that a C header file is
#included when the C code fragments in Green Card directives is
compiled. The %#include directive performs this delayed
#include. The syntax is exactly that of a C #include apart
from the initial %.