Implementing Array.make in OCaml-CodePudding

I am trying to implement Array.make of the OCaml Array module. However I'm not getting the values right, my implementation:

 let make_diy s v = 
         let rec aux s v = 
           if s = 0 then [| |]
           else Array.append v ( aux (s-1) v )
       in aux s v;;

...has the value: val make_diy : int -> 'a array -> 'a array = <fun>instead of: int -> 'a -> 'a array. It only creates an array if v is already in an array:

make_diy 10 [|3|];;
- : int array = [|3; 3; 3; 3; 3; 3; 3; 3; 3; 3|]

make_diy 10 3;;
Error: This expression has type int but an expression was expected of type
         'a array

I also tried to make it with an accumulator, but it has the same result:

let make_diy s v = 
         let rec aux s v acc =  
           if s=0 then acc
           else append v ( aux (s-1) v acc  )
       in aux s v [| |];;

EDIT: (typo) append instead of add

CodePudding user response：

The problem seems to be that Array.append expects two arrays. If you want to use it with just an element, you need to wrap the first argument into an array:

Array.append [| v |] (aux (s - 1) v)

Note that this isn't a particularly efficient way to build up an array. Each iteration will allocate a new, slightly larger array. But presumably this is just a learning exercise.