Not all functionality of the C-interface is provided, but as
PlTerm and term_t are
essentially the same thing with automatic type-conversion between the
two, this interface can be freely mixed with the functions defined for
plain C.
Using this interface rather than the plain C-interface requires a
little more resources. More term-references are wasted (but reclaimed on
return to Prolog or using PlFrame).
Use of some intermediate types (functor_t etc.) is not
supported in the current interface, causing more hash-table lookups.
This could be fixed, at the price of slighly complicating the interface.