Hi, with the following definitions {-# OPTIONS -fglasgow-exts #-} data a :++: b class a :--: b ghci prints the infix type(classe)s as prefix: *Main> :i :++: data :++: a b -- Defined at foo.hs:2:7 *Main> :i :--: class :--: a b where -- Defined at foo.hs:3:8 or (a "real-world" example): *Main> :t fac (One:@Zero:@Zero) fac (One:@Zero:@Zero) :: :@ (:@ (:@ (:@ One One) Zero) Zero) Zero Is this a bug, a feature or just Not Implemented Yet(TM)? Groeten, Remi P.S. Are infix class-names a documented extension at all? -- Nobody can be exactly like me. Even I have trouble doing it.