* Re: [Caml-list] applying labled argument error
2013-11-09 17:57 ` Jean Saint-Remy
@ 2013-11-09 18:39 ` Anthony Tavener
2013-11-09 18:42 ` Anil Madhavapeddy
1 sibling, 0 replies; 6+ messages in thread
From: Anthony Tavener @ 2013-11-09 18:39 UTC (permalink / raw)
To: Jean Saint-Remy; +Cc: Gabriel Kerneis, caml-list
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This is a bit of a pickle. For Real World OCaml to be a great book for
OCaml almost requires Core to become the stdlib. Core is a pretty nice body
of work, but I'm not a user of it myself, and I've been unable to decide if
I'd like it as the standard library. There is a very strong flavor to the
style. I suppose the official standard library has a bit of an
"exceptional" flavor, but aside from that I feel it doesn't impose anything.
Jean, for you example, the List.iter line using the standard library would
be:
List.iter (fun x -> sum := !sum + x) list;
This kind of confusion is certainly not good for learning a language
though! To resolve this, we need to clone a single person three times and
send each into an alternate future: one continuing with standard library
as-is, one with Core, and one with Batteries. Then bring them back so they
can argue amongst each other about what was better. :)
On Sat, Nov 9, 2013 at 10:57 AM, 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
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
>
>
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Caml-list] applying labled argument error
2013-11-09 17:57 ` Jean Saint-Remy
2013-11-09 18:39 ` Anthony Tavener
@ 2013-11-09 18:42 ` Anil Madhavapeddy
1 sibling, 0 replies; 6+ messages in thread
From: Anil Madhavapeddy @ 2013-11-09 18:42 UTC (permalink / raw)
To: Jean Saint-Remy; +Cc: Gabriel Kerneis, caml-list
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
>
> --
> Caml-list mailing list. Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread