Elm why you no check type alias

main.elm

import Html exposing (text)

type alias ID = Int
type alias Minute = Int

f : ID -> Int
f x = x * 2

g : Minute -> Bool
g x = if x > 10 then True else False


poo : {x:ID, y:Minute}
poo = { x = 5, y = 10 }

a : ID
a = 5

b : Minute
b = 10

c = g a
main =
  text (toString c)