[erlang-questions] A style question

Jayson Vantuyl kagato@REDACTED
Mon Feb 15 03:35:42 CET 2010

With respect to exports (#4), I just tested it with R13B, it doesn't appear that you have to export a fun to reference it.  Specifically, this works for me:

> -module(u).
> -export ([test/0]).
> test() ->
>   F = fun test2/0,
>   F().
> test2() ->
>   ok.

That said, I think point #5 is an important one, although maybe not for the reason you do.  I've noticed that some people have gaps in their knowledge of Erlang.  "fun somefunc/N" seems to be one of them.  Capturing surrounding variables is another one.

As for point #3, I don't know of many times I would consider "fun () -> .. end" to be anything but bulky.  Then again, Ruby and Python may have me spoiled in that respect.  Of course, that is definitely a matter of personal preference.

On Feb 14, 2010, at 6:06 PM, Richard O'Keefe wrote:

> On Feb 14, 2010, at 10:39 AM, Jayson Vantuyl wrote:
>> I've always felt that "fun some_func/2" is underused.
> It's a good thing to use _if_ you already have some_func/2 and
> don't need to pass it any arguments.
> We have agreement on a number of points.
> (1) If you introduce a name for a function that is passed to
>    a higher order operation, it should be a meaningful name,
>    not just "F" or "f" or anything like that.
> (2) If you already want to name a function for some other reason,
>    use fun F/N to refer to it rather than fun (X,...) -> F(X,...) end.
> (3) If the code would be bulky, _something_ has to move out and
>    it might as well be the 'fun'.
> (4) Having 'fun (..) -> end' available means we don't have to
>    export things just so they can be called, and having
>    'fun F/N' available means the same; exporting stuff we'd
>    rather not is no longer an issue.
> (5) If there is information in the surrounding clause that needs to
>    be passed in, one level of 'fun' to capture that seems to be
>    necessary, but it need not be the _whole_ of the computation;
>    you can hand the information off to something with a name and
>    a comment.
> I think we're now pretty much down to the "personal judgement"
> level.
> ________________________________________________________________
> erlang-questions (at) erlang.org mailing list.
> See http://www.erlang.org/faq.html
> To unsubscribe; mailto:erlang-questions-unsubscribe@REDACTED

Jayson Vantuyl

More information about the erlang-questions mailing list