With reference to the future of template haskell - it would be nice if you could express the following: stringType :: String -> Q [Dec] stringType s = do x <- gensym "x" y <- gensym "y" return [ Newtype [] s [] (Constr s [(Strict,Tcon (TconName "String"))]) [], Proto ("show"++s) (Tapp (Tapp (Tcon Arrow) (Tcon (TconName s))) (Tcon (TconName "ShowS"))), Fun ("show"++s) [Clause [Pcon s [Pvar x]] (Normal (App (Var "showString") (Var x))) []], Instance [] (Tapp (Tcon (TconName "Show")) (Tcon (TconName s))) [ Fun "showsPrec" [Clause [Pwild,Pvar x] (Normal (App (Var ("show"++s)) (Var x))) []]], Instance [] (Tapp (Tcon (TconName "Eq")) (Tcon (TconName s))) [ Fun "==" [Clause [Pcon s [Pvar x],Pcon s [Pvar y]] (Normal (App (App (Var "==") (Var x)) (Var y))) []]] ] AS stringType :: String -> Q [Dec] stringType s = [| newtype $s = $s String show$s :: $s -> ShowS show$s ($s x) = showString x instance Show $s where showsPrec _ x = show$s x instance Eq $s where ($s x) ($s y) = (x==y) |] Maybe with a more specific type like : stringType :: TypeName -> Q [Dec] where TypeName would enforce the first letter must be capital rule. NOTE: to work this would require show$s to crate a function name from show prepended to the type name... Why is this not possible with the current template-haskell, and would this be possible with the proposed extensions (if not, why not, as the above seems very easy to read?) Regards, Keead Schupke.