expected

This expression has multiple possible types.  Some examples:
λxs. each(λx. x + 1, xs) : List(ℕ) → List(ℕ)
λxs. each(λx. x + 1, xs) : Bag(ℕ) → Bag(ℕ)
λxs. each(λx. x + 1, xs) : Set(ℕ) → Set(ℕ)
λxs. each(λx. x + 1, xs) : List(ℤ) → List(ℤ)
λxs. each(λx. x + 1, xs) : Bag(ℤ) → Bag(ℤ)
λxs. each(λx. x + 1, xs) : Set(ℤ) → Set(ℤ)
λxs. each(λx. x + 1, xs) : List(𝔽) → List(𝔽)
λxs. each(λx. x + 1, xs) : Bag(𝔽) → Bag(𝔽)
...
This expression has multiple possible types.  Some examples:
λxs. each(list, xs) : List(List(a)) → List(List(a))
λxs. each(list, xs) : List(Bag(a)) → List(List(a))
λxs. each(list, xs) : List(Set(a)) → List(List(a))
λxs. each(list, xs) : Bag(List(a)) → Bag(List(a))
λxs. each(list, xs) : Bag(Bag(a)) → Bag(List(a))
λxs. each(list, xs) : Bag(Set(a)) → Bag(List(a))
λxs. each(list, xs) : Set(List(a)) → Set(List(a))
λxs. each(list, xs) : Set(Bag(a)) → Set(List(a))
...
each(λx. x + 1, [1, 2, 3]) : List(ℕ)
each(λx. x + 1, ⟅1, 2, 3⟆) : Bag(ℕ)
each(λx. x + 1, {1, 2, 3}) : Set(ℕ)
[2, 3, 4]
⟅2, 3, 4⟆
⟅0, 1 # 2, 4 # 2⟆
⟅1 # 100⟆
{2, 3, 4}
{0, 1, 4}
{1}