title: Mixed programming between scheme and C
body: <p>I'm reading the CSUG to learn the FFI of chez-scheme. So I may have some beginner's error.
  I just want to know is there some question of FFI.
  C have some type of data, just like char, float, double, int, functions, struct, union, or enumeration.
  But they are not existed in scheme.
  There is number, list, character, string and symbol. Or the <code>defstruct</code> macro</p>
  <p>Is there some not compatible between their data type.
  If it's exit, What's the solution of the FFI.</p>