:3:5: You can't mix polymorphic and unlifted bindings a = (# 1 #) Probable fix: use a bang pattern :4:5: You can't mix polymorphic and unlifted bindings a = (# 1, 3 #) Probable fix: use a bang pattern :1:1: GHCi can't bind a variable of unlifted type: a :: (# Integer, Integer #)