1 files changed, 57 insertions, 0 deletions
diff --git a/atom.h b/atom.h
new file mode 100644
index 0000000..3b716fa
--- /dev/null
+++ b/atom.h
@@ -0,0 +1,57 @@
+#ifndef ATOM_H
+#define ATOM_H
+
+#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_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
+
+#define CDR(LIST) ((LIST) != NULL ? (LIST)->next : NULL)
+#define CDDR(LIST) CDR(CDR(LIST))
+
+enum
+{
+    ATOM_NIL,
+    ATOM_INT,
+    ATOM_STR,
+    ATOM_SYMBOL,
+    ATOM_LIST
+};
+
+struct atom
+{
+    union
+    {
+        long l;
+        struct
+        {
+            char *str;
+            int len;
+        } 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);
+struct atom *atom_new_sym(const char *sym, int len);
+struct atom *atom_new_list(struct list *list);
+
+extern struct atom true_atom;
+extern struct atom false_atom;
+extern struct atom nil_atom;
+
+#endif