To put it another way, borrowing a geneaological term:
when initializing a seq with a set of inheritable types, the resulting type
will be that of the most recent common ancestor of those types.
type
Fish{.inheritable.} = ref object
RayFinnedFish = ref object of Fish
Tuna = ref object of RayFinnedFish
LobeFinnedFish = ref object of Fish
Coelacanth = ref object of LobeFinnedFish
Tetrapod = ref object of LobeFinnedFish
Human = ref object of TetraPod
Chicken = ref object of TetraPod
let adam = Human()
let eve = Human()
let fifi = Chicken()
let jack = Tuna()
assert typeof(@[adam,eve]) is seq[Human]
assert typeof(@[adam,fifi]) is seq[Tetrapod]
assert typeof(@[eve,adam,jack]) is seq[Fish]
Run
