type
  Vec[N: static[int], T] = object
    data: array[N, T]

proc newVec[N: static int, T](arr: array[N, T]): Vec[N,T] = discard

proc `+`[A: Vec](a: A; t: A.T): string = "A"
proc `+`[A: Vec](t: A.T; a: A): string = "B"

let v = newVec([0.0])
echo v + 1.0            # no problem
echo 1.0 + v            # error:  Cannot instantiate Vec[N,T] inside of type definition `+`