Batched a b -> Batched a ...?

[Quelklef]

Hypothesis:

data Batched a b = Single (a b) | Batch (Array (Batched a b))

can become

data Batched a = Single a | Batched (Array (Batched a))

We made this change and followed the type errors and were able to compile without anything suspicious coming up.

Mysterious...

Runtime behaviour was not tested.

[Quelklef]

Recording this here since it's been a question multiple times: the reason Batched is defined as

data BatchedF f a ≅ Array (f a)

instead of

data BatchedA a ≅ Array a

is because to transform the contained as we need only one map:

map :: forall f. Functor f => (a -> b) -> BatchedF f a -> BatchedF f b

instead of two:

(map >>> map) :: forall f. Functor f => (a -> b) -> BatchedA (f a) -> BatchedA (f b)

That is, it's convenience

[ursi]

What about

data BatchedA a ≅ Array a

and then using Compose for the nested case?