More work

INTERNAL ERROR: "Not a guess ? {ty2} : Type 0. (mor : {ty2}) ->
Prelude.Category.Category Type 0 (let {scvar0} : Type a = x -> y in
?defer Prelude.Category.case block in Type, case x -> y of mor x y =>
mor instance of Prelude.Category.Category : Type 0 -> Type a -> ({ty2} :
Type 0) -> {ty2} -> Type a -> Type 0 -> Type 0 -> Type 0.
Prelude.Category.case block in Type, case x -> y of mor x y => mor
instance of Prelude.Category.Category x y {ty2} mor
{scvar0})\n([{ty2},{hole2},{hole1},{hole0}],?? {hole0} : Type 0 = (x :
Type 0) -> ?? {hole1} : Type 0 = (y : Type a) -> ?? {hole2} : Type 0 = ?
{ty2} : Type 0. (mor : {ty2}) -> Prelude.Category.Category Type 0 (let
{scvar0} : Type a = x -> y in ?defer Prelude.Category.case block in
Type, case x -> y of mor x y => mor instance of
Prelude.Category.Category : Type 0 -> Type a -> ({ty2} : Type 0) ->
{ty2} -> Type a -> Type 0 -> Type 0 -> Type 0. Prelude.Category.case
block in Type, case x -> y of mor x y => mor instance of
Prelude.Category.Category x y {ty2} mor {scvar0}) in {hole2} in {hole1}
in {hole0})"
This is probably a bug, or a missing error message.