Add identifier interning and keyword lexing

meta.c

@@ -1,7 +1,9 @@
 #include <stdio.h>
-
-#define len(x) (sizeof((x))/sizeof((x)[0]))
-#define ilen(x) ((int)len(x))
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "base.c"
 
 int main() {
     typedef struct {