# #use "vector.ml";;
type 'a vector = { length : int; vec : 'a array; }
val get : 'a vector -> int -> 'a = <fun>
# let z={length=1; vec=Array.make 1 1};;
val z : int vector = {length = 1; vec = [|1|]}
# let valueo = getIndex 0 z;;
Error: This expression has type int vector/1035
       but an expression was expected of type unit vector/1018