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3 points by almkglor 4151 days ago | link | parent

True, which is why I was always a bit leery of the trick. Besides, if you're going to implement bignums anyway, you might as well start off "fixnums" as very small bignums ^^. LOL. Of course there's the obvious problem that most applications won't use bignums, and in applications that do, most numbers still aren't bignums.

But then, if you add two fixnums together and the result won't fit in a fixnum...

As an aside, in the current mzscheme implementation, it seems fixnums are type 'int and everything else is type 'num

Finally: if you need to access call* , it may be possible to determine its position in GLOBAL() and add a C-global CALL_STAR:

  ; in codegen...
  (list
     "obj * CALL_STAR;"
     ...
     "int main(){
     CALL_STAR = &GLOBAL(" (pos [is _!uid 'call*] global-vars) ");
     initialize_constants();
     execute(0);
     }")
Quite obviously the unused global elimination step will have to avoid eliminating 'call* though.

Edit: regarding typing closures: I've been reading about flexible array members of structs, so it might be possible to define the closure type as:

  struct{
    long type; /* T_FN */
    obj vars[];
  } closure_type;
For non-C99 compliant compilers (practically everything except GCC), though, you need:

  struct{
    long type; /* T_FN */
    obj vars[1];
  } closure_type;