added better repl message

main.c

@@ -1457,6 +1457,7 @@ int main(int argc, char* const* argv)
     else
     {
         // Let's humble-brag just a little.
+        #if 0
         {
             int max_cost = 0;
 
@@ -1475,9 +1476,20 @@ int main(int argc, char* const* argv)
                 max_cost);
             puts("");
         }
+        #endif
+        
+        if (!quiet)
+        {
+            puts("Use C-style syntax for boolean operators and expressions.");
+            puts("Available variables: 'w', 'x', 'y' and 'z'.");
+            puts("Extended operators: nor is '!|', orn is '|!', nand is '!&', andn is '&!'.");
+        }
+
         
         for (char* line; (line = readline(">>> ")); free(line))
         {
+            if (!*line) continue;
+            
             add_history(line);
             
             uint16_t truthtable = evaluate(line);
@@ -1490,7 +1502,8 @@ int main(int argc, char* const* argv)
             }
             else
             {
-                printf("%2i: ", lookup[truthtable].cost), print(truthtable, 0), puts("");
+                printf("%2i: ", lookup[truthtable].cost),
+                    print(truthtable, 0), puts("");
             }
         }
     }