add atom types for true, false, nil

2 files changed, 12 insertions, 7 deletions

diff --git a/atom.c b/atom.c
index 73ecd7e..375bd3e 100644
--- a/atom.c
+++ b/atom.c
@@ -4,9 +4,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-struct atom true_atom;
-struct atom false_atom;
-struct atom nil_atom;
+struct atom true_atom = { ATOM_TRUE };
+struct atom false_atom = { ATOM_FALSE };
+struct atom nil_atom = { ATOM_NIL } ;
 
 struct atom *atom_new(char type)
 {
diff --git a/atom.h b/atom.h
index 3b716fa..62e3276 100644
--- a/atom.h
+++ b/atom.h
@@ -4,13 +4,16 @@
 #define LIST_GET_ATOM(LIST) ((struct atom *) (LIST)->data)
 
 #define ATOM_TYPE(LIST) ((LIST_GET_ATOM(LIST))->type)
+
 #define IS_INT(LIST) ((ATOM_TYPE(LIST)) == ATOM_INT)
 #define IS_STR(LIST) ((ATOM_TYPE(LIST)) == ATOM_STR)
 #define IS_SYM(LIST) ((ATOM_TYPE(LIST)) == ATOM_SYMBOL)
 #define IS_LIST(LIST) ((ATOM_TYPE(LIST)) == ATOM_LIST)
+#define IS_ATOM(LIST) (!(IS_LIST(LIST)))
 
 #define IS_TRUE(LIST) (LIST_GET_ATOM(LIST) == &true_atom)
 #define IS_FALSE(LIST) (LIST_GET_ATOM(LIST) == &false_atom)
+
 #define IS_NIL(LIST) (LIST_GET_ATOM(LIST) == &nil_atom)
 
 #define CAR(LIST) LIST
@@ -24,11 +27,16 @@ enum
     ATOM_INT,
     ATOM_STR,
     ATOM_SYMBOL,
-    ATOM_LIST
+    ATOM_LIST,
+    ATOM_TRUE,
+    ATOM_FALSE
 };
 
+struct list;
+
 struct atom
 {
+    char type;
     union
     {
         long l;
@@ -39,11 +47,8 @@ struct atom
         } str;
         struct list *list;
     };
-    char type;
 };
 
-struct list;
-
 struct atom *atom_new(char type);
 struct atom *atom_new_int(long l);
 struct atom *atom_new_str(const char *str, int len);