--- stack/stack.h	2002/03/10 20:08:47	1.10
+++ stack/stack.h	2002/03/14 10:39:11	1.14
@@ -25,6 +25,7 @@
 /* First, define some types. */
 
 struct cons_struct;
+struct symbol_struct;
 
 /* A value of some type */
 typedef struct {
@@ -33,23 +34,24 @@
     tfloat,
     string,
     func,			/* Function pointer */
-    symb, 
-    tcons
+    symb,			/* Symbol */
+    tcons			/* A pair of two values */
   } type:4;			/* Type of stack element */
 
   union {
     struct {
-      unsigned int mark:1;
-      unsigned int protect:1;
+      unsigned int mark:1;	/* Used internally in the GC */
+      unsigned int protect:1;	/* Protect from GC */
     } flag;
-    unsigned int no_gc:2;
-  } gc;
+    unsigned int no_gc:2;	/* Both flags as one integer */
+  } gc;				/* Garbage collector stuff */
 
   union {
-    struct cons_struct *c;
     void *ptr;			/* Pointer to the content */
+    struct cons_struct *c;	/* ...or a pointer to a cons cell */
+    struct symbol_struct *sym;	/* ...or a pointer to a symbol */
     int i;			/* ...or an integer */
-    float f;
+    float f;			/* ...or a floating point number */
   } content;			/* Stores a pointer or an integer */
 
 } value;
@@ -62,7 +64,7 @@
   struct stackitem_struct *next; /* Next item */
 } stackitem;
 
-typedef struct cons_struct {
+typedef struct cons_struct {	/* A pair of two values */
   value *car;
   value *cdr;
 } cons;
@@ -85,7 +87,7 @@
   stackitem *gc_ref;
   int gc_limit, gc_count;
 
-  cons *head;		/* Head of the stack */
+  value *head;			/* Head of the stack */
   hashtbl symbols;		/* Hash table of all variable bindings */
   int err;			/* Error flag */
   char *in_string;		/* Input pending to be read */
@@ -116,12 +118,12 @@
 void push_sym(environment*, const char*);
 extern void nl();
 extern void type(environment*);
-void print_h(cons*, int);
+void print_h(value*, int);
 extern void print_(environment*);
 extern void print(environment*);
 extern void princ_(environment*);
 extern void princ(environment*);
-void print_st(cons*, long);
+void print_st(value*, long);
 extern void printstack(environment*);
 extern void swap(environment*);
 extern void rot(environment*);
@@ -164,3 +166,4 @@
 extern void sx_3c3d(environment*);
 extern void sx_3e3d(environment*);
 extern void sx_646976(environment*);
+extern void then(environment*);