<div dir="ltr">Why is the following not allowed?<div><br></div><div><div><font face="courier new, monospace">{-# LANGUAGE ExistentialQuantification, ExplicitForAll, RankNTypes, FlexibleInstances #-}</font></div><div><font face="courier new, monospace"><br>
</font></div><div><font face="courier new, monospace">class Class a where</font></div><div><font face="courier new, monospace"> test :: a -> Bool</font></div><div><font face="courier new, monospace"><br></font></div>
<div>
<font face="courier new, monospace">instance Class (forall m. m -> m) where</font></div><div><font face="courier new, monospace"> test _ = True</font></div><div><font face="courier new, monospace"><br></font></div><div>
<font face="courier new, monospace">main = do</font></div><div><font face="courier new, monospace"> putStrLn $ test id</font></div></div><div><br></div><div>Is there a reason that this is forbidden? Just curious.</div><div>
<br></div><div>-- Andrew</div></div>