Hello again, Thanks to Alastair Reid for your excellent response for my previous question !!! The concrete question now is: The order of constraints in a class definition are important? ======================================================= ========= More info can look here ===================== ======================================================= I'm try to look for the infinte loop in my previous example and i can't find it anywhere, but i discover that investing the order of the constranints in a class definition, the infinite loop disappears and program now works fine, i.e.: if i replace
class (Rule e r, SubResult r) => SubRule e r where ...
by
class (SubResult r, Rule e r) => SubRule e r where ...
the infinite loop error disappears Then, the order of constraints in a class definition are important? Saludos, Pablo_pc Cardenal Student at UNLP, La Plata, Buenos Aires, Argentina.