<div dir="ltr"><div class="gmail_extra">Hello,</div><div class="gmail_extra"><br></div><div class="gmail_extra">This is not an issue with MultiParamTypeClasses. It's just that type synonyms always have to be used fully applied. You can use a newtype instead:</div><div class="gmail_extra"><br></div><div class="gmail_extra"><span style="font-size:12.8px">newtype AdjList a = AdjList [(a,[a])]</span><br></div><div class="gmail_extra"><span style="font-size:12.8px"><br></span></div><div class="gmail_extra"><span style="font-size:12.8px">instance Graph AdjList Int where</span><span style="font-size:12.8px"><br></span></div><div class="gmail_extra"><span style="font-size:12.8px">  (...)</span></div><div class="gmail_extra"><span style="font-size:12.8px"><br></span></div><div class="gmail_extra"><span style="font-size:12.8px">Best regards,</span></div><div class="gmail_extra"><span style="font-size:12.8px">Marcin Mrotek</span></div><div class="gmail_extra"><br></div></div>