<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Still exploring monads. I don't understand why the type signature for double is OK, but not the one for iota.<br><br>Michael<br><br>=================<br><br>--double :: (Int a) => a -> Maybe b<br>--double x = Just (x + x)<br><br>iota :: (Int a) => a -> [b]<br>iota n = [1..n]<br><br>--usage: [3,4,5] >>= iota<br>--should produce [1,2,3,1,2,3,4,1,2,3,4,5]</td></tr></table><br>