T3330c.hs:23:43:
Couldn't match type `f1' with `f1 x'
`f1' is a rigid type variable bound by
a pattern with constructor
RSum :: forall (f :: * -> *) (g :: * -> *).
R f -> R g -> R (f :+: g),
in an equation for plug'
at T3330c.hs:23:8
In the first argument of `plug', namely `rf'
In the first argument of `Inl', namely `(plug rf df x)'
In the expression: Inl (plug rf df x)
T3330c.hs:23:43:
Couldn't match type `Der ((->) x)' with `R'
In the first argument of `plug', namely `rf'
In the first argument of `Inl', namely `(plug rf df x)'
In the expression: Inl (plug rf df x)