I noticed that GHC 6.2.2 always parse infix operators as they were left-associative. For example: %%%%% Prelude> :info : -- : is a data constructor infixr 5 : (:) :: forall a. a -> [a] -> [a] Prelude> 1:2:3:[] ==================== Parser ==================== ((1 GHC.Base.: 2) GHC.Base.: 3) GHC.Base.: GHC.Base.[] [1,2,3] %%%%% I suppose that the parse tree is then "fixed" in a later stage. (Or maybe the parse tree is fine but it gets unparsed in the wrong way?) However, the output above is a bit puzzling to me. Should I report this as a minor bug or is this the intended output? Thanks to your attention, Zun.