Procedures written in C can be registered for use from Scheme,
provided they take only arguments of type
SCM and return
scm_c_define_gsubr is likely to be the most
useful mechanism, combining the process of registration
scm_c_make_gsubr) and definition (
Register a C procedure FCN as a “subr” — a primitive subroutine that can be called from Scheme. It will be associated with the given name but no environment binding will be created. The arguments req, opt and rst specify the number of required, optional and “rest” arguments respectively. The total number of these arguments should match the actual number of arguments to fcn. The number of rest arguments should be 0 or 1.
scm_c_make_gsubrreturns a value of type
SCMwhich is a “handle” for the procedure.
Register a C procedure FCN, as for
scm_c_make_gsubrabove, and additionally create a top-level Scheme binding for the procedure in the “current environment” using
scm_c_define_gsubrreturns a handle for the procedure in the same way as
scm_c_make_gsubr, which is usually not further required.
scm_c_make_subr and also
scm_makcclo if necessary.
It is advisable to use the gsubr variants since they provide a
slightly higher-level abstraction of the Guile implementation.