title: ANTLR4 Modularization of DSL
body: <p>I am currently considering modularizing my DSL built with <code>ANTLR4</code>. This language is very simple at the moment, but is supposed to grow.</p>
  <p>Currently I have a <code>Format.g4 (Parser,Lexer)</code> and also an <code>Expression.g4 (Parser,Lexer)</code>.</p>
  <p>Is it possible in ANTLR4 to connect them with each other through an import and use them mutually? If they can be imported, do we have to work with an alias or similar to avoid collisions?</p>
  <p>I am planning other languages where <code>Expression.g4</code> will be used. These should not be maintained twice if possible.</p>