lean4-htt/tests/lean/run/IO2.lean

13 lines
392 B
Text

import system.io
open list
/- B and unit must be in the same universe
So, we must put B at Type₁ or use poly_unit
since unit is at Type₁
-/
definition foreach {A : Type} {B : Type} : list A → (A → io B) → io poly_unit
| [] f := return poly_unit.star
| (x::xs) f := do f x, foreach xs f
vm_eval foreach [1,2,3,4,5] (λ i, do put_str "value: ", put_nat i, put_str "\n")