I think the &quot;show a simple type, then the &#39;real&#39; type &quot; solution is pretty good ( especially since you need to be doing type level programming to hit issues where the simple type doesn&#39;t hold anyways) , but on the topic of several languages: doesn&#39;t  Haskell98 kind of solve the teaching issue? If you&#39;re using the standard stuff stick to the old $...<div><br></div><div>I know Racket does some &quot;language swapping&quot; so that a beginner language is available . I don&#39;t know how well that works</div>