:1:1: error: Variable not in scope: nubBy :1:1: error: Variable not in scope: nub :1:1: error: Variable not in scope: nubBy :1:1: error: Variable not in scope: nub :1:1: error: Variable not in scope: nub Perhaps you meant ‘L.nub’ (imported from Data.List) :1:1: error: Not in scope: ‘L.nub’ No module named ‘L’ is imported. :1:1: error: Variable not in scope: nub