I&#39;d like to be sure when one defines a type with &quot;type&quot;, it truly merely creates a synonym, and no matter what one could replace the left side by the right side in the whole program, and vice versa, and it wouldn&#39;t change a thing in the actual meaning, value of the program.<br><br>Eg if i define:<br>type In2 t = t -&gt; t -&gt; t<br>I can thereafter replace for any type t, any signature like<br>f :: t -&gt; t -&gt; t<br>with<br>f :: In2 t<br>then strictly no consequence other than visual in the source code, by me, will occur.<br>Thanks!