"group' n rest" is returning 'a array list, not 'a array array.

firstN: int -> 'a array -> 'a array * 'a array
group': int -> 'a array -> 'a array list
group: int -> 'a array -> 'a array array

---
SooHyoung Oh
----- Original Message -----
From: "Ryan Bastic" <rbastic@gis.net>
To: <caml-list@inria.fr>
Sent: Friday, April 18, 2003 12:25 PM
Subject: [Caml-list] Clarification on some ocaml stuff


> Hello all,
>   A few weeks ago I posted a message asking how to create a program in
> OCaml to shuffle  vector of strings into an array of arrays. Had some
> problems understanding how to do it in Ocaml properly, and a kind soul
> posted a very elegant solution to the problem :-) unfortunately, i still
> can't understand some things from it.
>
>   What follows is some code with comments on how it is expected to be
> used, and also
> where my confusion in the semantics of the code lay.
>
>   (* Return first 'n' from input and the rest. *)
> let firstN n input =
>   let nInput = Array.length input in
>     if n >= nInput
>     then (input, [||])
>     else (Array.sub input 0 n, Array.sub input n (nInput - n))
>
> let group n input =
>   let rec group' n input =
>     if Array.length input = 0 then []
>     else
>       let (front, rest) = firstN n input in
>         (* the next line confuses me. i'm aware of :: being a list
> concatenation
>            operator, but in this case, shouldn't group 'n rest be
> returning an array,
>            because that's what firstN returns. I've experimented in the
> REPL and had
>            no luck in figuring it out. *)
>     front :: group' n rest
>   in
>     Array.of_list (group' n input)
>
> if you pop this into the toplevel, and do:
>
> group 2 [|"Name1"; "Name2"; "Name3"; "Name4"; "Name5";|];;
>
> you'll see the general functionality expected.
>
> thanks for any help,
> -Ryan
> http://malander.undrgnd.net
>
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