[racket] `provide` failed under `#lang racket/load`

On Sun, Aug 4, 2013 at 10:40 AM, Carl Eastlund <cce at ccs.neu.edu> wrote:

> On Sun, Aug 4, 2013 at 4:32 AM, Yi Dai <plmday at gmail.com> wrote:
>
>>
>>
>>
>> On Sun, Aug 4, 2013 at 10:20 AM, Carl Eastlund <cce at ccs.neu.edu> wrote:
>>
>>> Yi,
>>>
>>> Most #lang languages implicitly create a module from the contents of the
>>> file.  #lang racket/load, on the other hand, runs the contents of the file
>>> as top-level terms outside of any module.  The provide form is not legal at
>>> the top level, as it is meaningless -- there's no module to provide things
>>> from.  You need to either switch back to #lang racket or remove the
>>> provide, depending on what you're trying to accomplish.
>>>
>>
>> Thanks for the answer, Karl.  I also found the answer in the doc:
>> http://docs.racket-lang.org/reference/load-lang.html.  But very
>> confusingly, the doc keeps saying "racket/load" module.
>>
>
> Yes, the file is technically a module.  However, the code you write is not
> evaluated in the context of that module.  It is instead evaluated in a
> dynamically-generated top-level context.  It might be clearer if we look at
> the explicit module generated by the two #lang languages:
>
> #lang racket
> <code1>
> <code2>
> ...
>
> is equivalent to
>
> (module <filename> racket
>   <code1>
>   <code2>
>   ...)
>
> However,
>
> #lang racket/load
> <code1>
> <code2>
> ...
>
> is (basically) equivalent to
>
> (module <filename> racket
>   (eval (quote <code1>))
>   (eval (quote <code2>))
>   ...)
>

Ah, now it is clearer.  Thanks a lot, Karl.


>
>
>>
>>
>>> On Sun, Aug 4, 2013 at 4:12 AM, Yi Dai <plmday at gmail.com> wrote:
>>>
>>>>  Hi,
>>>>
>>>>
>>>> I have the following code in a file named `foo.rkt`:
>>>>
>>>> ```
>>>> #lang racket/load
>>>>
>>>> (provide foo)
>>>>
>>>> (define foo 'bar)
>>>> ```
>>>>
>>>> When trying to run the code, I got the following confusing error:
>>>>
>>>> > `provide`: not at module level in: `(provide foo)`
>>>>
>>>> What does this mean?  Why `provide` is not at module level?
>>>> Use `#lang racket` instead does not pose this problem.  I am
>>>> confused.  Any idea?
>>>>
>>>>
>>>> Yours truly,
>>>>
>>>> Yi
>>>>
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>>>>   http://lists.racket-lang.org/users
>>>>
>>>>
>>>
>>
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>>
>
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