added a couple of comments

main.cpp

@@ -223,7 +223,7 @@ namespace M { //M-Expressions
 }
 
 int main() {
-/*
+/* Human-readable version of the following expression
 Eval[
 	((LABEL Atom0
 		(LAMBDA (Atom1 Atom2) (COND
@@ -320,7 +320,7 @@ Eval[
 			S::NIL> >,
 		S::NIL> > >,
 		S::NIL
-	>::value typedef X;
-	X::print_by_error;
+	>::value typedef X; //X is the result of the computation
+	X::print_by_error; //print_by_error doesn't exist, so a compiler with good feedback will represent the type "X" in an error
 	return 0;
 }