λxs. each(λx. x + 1, xs) : List(ℕ) → List(ℕ)
λxs. each(list, xs) : List(List(a)) → List(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}