Issue #377

gc.c

@@ -968,6 +968,7 @@ char *gc_copy_obj(object dest, char *obj, gc_thread_data * thd)
   case forward_tag:
     return (char *)forward(obj);
   case eof_tag:
+  case void_tag:
   case primitive_tag:
   case boolean_tag:
   case symbol_tag:

include/cyclone/runtime.h

@@ -31,6 +31,12 @@ extern const object quote_void;
  */
 extern const object Cyc_EOF;
 
+/**
+ * The void value.
+ * \ingroup objects
+ */
+extern const object Cyc_VOID;
+
 /**
  * \ingroup gc_minor
  */
@@ -480,6 +486,7 @@ object Cyc_is_procedure(void *data, object o);
 //object Cyc_is_opaque(object o);
 #define Cyc_is_macro(o)       (make_boolean(is_object_type(o) && ((list) o)->tag == macro_tag))
 #define Cyc_is_eof_object(o)  (make_boolean(is_object_type(o) && ((list) o)->tag == eof_tag))
+#define Cyc_is_void_object(o) (make_boolean(is_object_type(o) && ((list) o)->tag == void_tag))
 #define Cyc_is_cvar(o)        (make_boolean(is_object_type(o) && ((list) o)->tag == cvar_tag))
 #define Cyc_is_opaque(o)      (make_boolean(is_object_type(o) && ((list) o)->tag == c_opaque_tag))
 object Cyc_is_immutable(object obj);

include/cyclone/types.h

@@ -69,6 +69,7 @@ enum object_tag {
       , vector_tag      = 20
       , complex_num_tag = 21
       , atomic_tag      = 22
+      , void_tag        = 23
 };
 
 /**

runtime.c

@@ -48,7 +48,8 @@ const char *tag_names[] = {
       /*symbol_tag    */ , "symbol"
       /*vector_tag    */ , "vector"
       /*complex_num_tag*/ , "complex number"
-      /*atomic_tag*/ , "atomic"
+      /*atomic_tag*/     , "atomic"
+      /*void_tag*/       , "void"
   , "Reserved for future use"
 };
 
@@ -190,8 +191,10 @@ int _cyc_argc = 0;
 char **_cyc_argv = NULL;
 
 static symbol_type __EOF = { {0}, eof_tag, ""};  // symbol_type in lieu of custom type
+static symbol_type __VOID = { {0}, void_tag, ""};  // symbol_type in lieu of custom type
 
 const object Cyc_EOF = &__EOF;
+const object Cyc_VOID = &__VOID;
 static ck_hs_t lib_table;
 static ck_hs_t symbol_table;
 static int symbol_table_initial_size = 4096;
@@ -1033,6 +1036,8 @@ object Cyc_display(void *data, object x, FILE * port)
   case eof_tag:
     fprintf(port, "<EOF>");
     break;
+  case void_tag:
+    break;
   case port_tag:
     fprintf(port, "<port %p>", ((port_type *) x)->fp);
     break;
@@ -5857,6 +5862,7 @@ static char *gc_move(char *obj, gc_thread_data * thd, int *alloci, int *heap_gro
   case forward_tag:
     return (char *)forward(obj);
   case eof_tag:
+  case void_tag:
     break;
   case primitive_tag:
     break;
@@ -6034,6 +6040,7 @@ int gc_minor(void *data, object low_limit, object high_limit, closure cont,
       break;
       // These types are not heap-allocated
     case eof_tag:
+    case void_tag:
     case primitive_tag:
     case symbol_tag:
     case boolean_tag:
@@ -6100,6 +6107,7 @@ void Cyc_make_shared_object(void *data, object k, object obj)
   //  symbol_tag      = 19
   //  closure0_tag    = 3
   //  eof_tag         = 9
+  //  void_tag
   //  macro_tag       = 13
   //  primitive_tag   = 17
 

scheme/base.sld

@@ -178,6 +178,7 @@
     exact
     inexact
     eof-object
+    void
     syntax-error
     bytevector-copy
     bytevector-copy!
@@ -1444,6 +1445,11 @@
     " return_closcall1(data, k, Cyc_EOF); "
     "(void *data, object ptr)"
     " return Cyc_EOF;")
+  (define-c void
+    "(void *data, int argc, closure _, object k)"
+    " return_closcall1(data, k, Cyc_VOID); "
+    "(void *data, object ptr)"
+    " return Cyc_VOID;")
   (define-c input-port?
     "(void *data, int argc, closure _, object k, object port)"
     " port_type *p = (port_type *)port;