+class GArrow g (**) u => GArrowDrop g (**) u where
+ ga_drop :: g x u
+
+class GArrow g (**) u => GArrowSwap g (**) u where
+ ga_swap :: g (x**y) (y**x)
+
+ga_swap_second f =
+ ga_swap >>> ga_first f >>> ga_swap
+ -- implementation of ga_second for GArrowSwap
+ -- See also
+ -- http://haskell.org/haskellwiki/Class_system_extension_proposal
+ -- "Allowing superclass methods to be overridden in derived classes";
+ -- if we had this we could do a better job here
+
+
+
+------------------------------------------------------------------------
+-- Products, Coproducts, etc
+
+
+class (GArrow g (**) u,
+ GArrow g (<*>) u) =>
+ GArrowProd g (**) u (<*>) where
+ ga_prod_copy :: g x (x<*>x)
+ ga_prod_drop :: g x u
+
+class (GArrow g (**) u,
+ GArrow g (<+>) v) =>
+ GArrowSum g (**) u v (<+>) where
+ ga_merge :: g (x**x) x
+ ga_never :: g v x
+
+
+
+
+
+------------------------------------------------------------------------
+-- Loop
+
+class GArrow g (**) u => GArrowLoop g (**) u where
+ ga_loopl :: g (x**z) (y**z) -> g x y
+ ga_loopr :: g (z**x) (z**y) -> g x y
+
+
+------------------------------------------------------------------------
+-- Literal. Note that ga_literal should never appear in (unflattened)
+-- Haskell programs, though the user may wish to write implementations
+-- of this function (I haven't yet found a way to enforce this
+-- restriction using exports)
+
+class GArrow g (**) u => GArrowLiteral g (**) u t r where
+ ga_literal :: t -> g u r
+