I just consider the reasoning and I agree with both:
Haskell is big on partial application. It makes sense to use this with the error type to get a specialized result type.
Rust's ordering is more natural though.
I do hate the name "Either" though. It makes both options sound too 'equal'.
![ghci> data TreeL a = LeafL | NodeL a (TreeL a) (TreeL a) deriving (Show, Eq, Functor, Foldable)
ghci> data TreeM a = LeafM | NodeM (TreeM a) a (TreeM a) deriving (Show, Eq, Functor, Foldable)
ghci> foldr (:) [] $ NodeL 2 (NodeL 1 LeafL LeafL) (NodeL 3 LeafL LeafL)
[2,1,3]
ghci> foldr (:) [] $ NodeM (NodeM LeafM 1 LeafM) 2 (NodeM LeafM 3 LeafM)
[1,2,3]](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:zsixmktpv5u33kcnqk623vk3/bafkreicvmysxrw36mhayg2bzewhjkifumpif3b6fx527z3q6yw2mvut37a)
