Re: [Caml-list] applying labled argument error

[Anil Madhavapeddy <anil@recoil.org>]

Dear Jean,

Please do go through the installation instructions at:
https://realworldocaml.org/install

The Real World OCaml tutorials assume that you use the "utop" toplevel rather than than the standard toplevel.  You also need to "open Core.Std" at the beginning of the toplevel to ensure that you're using the Core standard library.

So you need:

$ utop
# open Core Std ;;
# let sum list = 
  let sum  = ref 0 in 
  List.iter list ~f:(fun x -> sum := !sum + x);
  !sum ;;
val sum : int list -> int = <fun> 

It's possible to use the standard OCaml toplevel if you really want to, but you need to manually configure several settings that Utop sets by default (short-paths, and evaluation of Async Deferred.t values at the toplevel).

best,
Anil

On 9 Nov 2013, at 09:57, Jean Saint-Remy <jeansaintremy@yahoo.com> wrote:

> Hi,
> 
> I've been working out some of the examples in the https://realworldocaml.org/v1/en/html/a-guided-tour.html, which does utilize JaneStreet 'core' library. The new ocaml website is very impressive, as it allows you to dive right in into very fascinating idiomatic ocaml expressions. Just launching ocaml toplevel though is not enough. 
> 
> let sum list = 
>   let sum  = ref 0 in 
>   List.iter list ~f:(fun x -> sum := !sum + x);
>   !sum ;;
> -: Error: The function applied to this argument has type 'a list -> unit
>    This argument cannot be applied with label ~f
> 
> Jean
> 
> 
> On Saturday, November 9, 2013 5:07 AM, Gabriel Kerneis <gabriel@kerneis.info> wrote:
> On Fri, Nov 08, 2013 at 07:33:35PM -0800, Jean Saint-Remy wrote:
> > I am running ocaml 3.12.1 and getting an error message. Is it an incompatible
> > version error or a missing 'core' module?
> 
> Since you mention 'core', are you learning OCaml with "Real-World OCaml" (and
> hence trying to use JaneStreet's Core library instead of the standard one)?
> That would explain the discrepancy you are seeing.
> 
> 
> Best,
> 
> -- 
> Gabriel
> 
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