[racket] users Digest, Vol 109, Issue 76

Please take me off the list

Thanks

On Mon, Sep 29, 2014 at 12:00 PM,  <users-request at racket-lang.org> wrote:
> Send users mailing list submissions to
>         users at racket-lang.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         http://lists.racket-lang.org/users/listinfo
> or, via email, send a message with subject or body 'help' to
>         users-request at racket-lang.org
>
> You can reach the person managing the list at
>         users-owner at racket-lang.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of users digest..."
>
>
> [Racket Users list:
>  http://lists.racket-lang.org/users ]
>
>
> Today's Topics:
>
>    1.  Is there any way to get the bit depth of a bitmap? (rrandom)
>    2. Re: Is there any way to get the bit depth of a bitmap?
>       (Matthew Flatt)
>    3. Re: rsound docs (Matthew Flatt)
>    4. Re: typed racket, filters, and polymorphism (Robby Findler)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 29 Sep 2014 23:14:43 +0800
> From: rrandom <emanonhere at gmx.com>
> To: Racket Users <users at racket-lang.org>
> Subject: [racket]  Is there any way to get the bit depth of a bitmap?
> Message-ID: <54297763.3020407 at gmx.com>
> Content-Type: text/plain; charset=GB2312
>
> Hi,I am recently working in the book Digital Image Processing with
> racket. I want to know is there any way to get the bit depth or color
> depth of a input bitmap in Racket? I found the get-depth method in
> racket/draw,bitmap%, but it only return 1 and 32, that's not what i
> really want.I input a bitmap whose bit depth is 8 but i got 32.
> following is the code:
>
>> (send (read-bitmap "Fig0305(a)(DFT_no_log).tif")
> get-depth)
> 32
>
> Is there anything I am wrong? Thank you!
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 29 Sep 2014 09:24:07 -0600
> From: Matthew Flatt <mflatt at cs.utah.edu>
> To: rrandom <emanonhere at gmx.com>
> Cc: Racket Users <users at racket-lang.org>
> Subject: Re: [racket] Is there any way to get the bit depth of a
>         bitmap?
> Message-ID: <20140929152408.F0E42650192 at mail-svr1.cs.utah.edu>
> Content-Type: text/plain; charset=UTF-8
>
> Racket libraries can read and write images of various formats and
> pixels depths, but a `bitmap%` object always represents an image using
> 1 or 32 bits per pixel in memory.
>
> At Mon, 29 Sep 2014 23:14:43 +0800, rrandom wrote:
>> Hi,I am recently working in the book Digital Image Processing with
>> racket. I want to know is there any way to get the bit depth or color
>> depth of a input bitmap in Racket? I found the get-depth method in
>> racket/draw,bitmap%, but it only return 1 and 32, that's not what i
>> really want.I input a bitmap whose bit depth is 8 but i got 32.
>> following is the code:
>>
>> > (send (read-bitmap "Fig0305(a)(DFT_no_log).tif")
>> get-depth)
>> 32
>>
>> Is there anything I am wrong? Thank you!
>> ____________________
>>   Racket Users list:
>>   http://lists.racket-lang.org/users
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 29 Sep 2014 09:28:14 -0600
> From: Matthew Flatt <mflatt at cs.utah.edu>
> To: C K Kashyap <ckkashyap at gmail.com>
> Cc: users at racket-lang.org
> Subject: Re: [racket] rsound docs
> Message-ID: <20140929152815.C87E6650194 at mail-svr1.cs.utah.edu>
> Content-Type: text/plain; charset=UTF-8
>
> When you install the package, you also install documentation for
> RSound. You should be able to find it by selecting "Racket
> Documentation" from the "Help" menu in DrRacket, by right-clicking on
> an identifier in DrRacket that is provided by the package's library, or
> by running `raco docs` on the command line.
>
> You can also find documentation linked from the "rsound" entry at
> http://pkgs.racket-lang.org/, which goes to
>
>   http://pkg-build.racket-lang.org/doc/rsound/index.html
>
>
> At Mon, 29 Sep 2014 19:09:17 +0530, C K Kashyap wrote:
>> Hi,
>>
>> I saw this nice racketcon video (
>> https://www.youtube.com/watch?v=DkIVzHNjNEA&list=PLXr4KViVC0qI9t3lizitiFJ1cFIeN2
>> Gdh&index=9)
>> on rsound. I've installed the rsound package and have been able to run the
>> example from the video.
>>
>> Is there a place that has mode documentation/tutorial on rsound?
>>
>> Regards,
>> Kashyap
>> ____________________
>>   Racket Users list:
>>   http://lists.racket-lang.org/users
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 29 Sep 2014 10:40:08 -0500
> From: Robby Findler <robby at eecs.northwestern.edu>
> To: Konrad Hinsen <konrad.hinsen at fastmail.net>
> Cc: racket users list <users at racket-lang.org>
> Subject: Re: [racket] typed racket, filters, and polymorphism
> Message-ID:
>         <CAL3TdOPrHreseE2RxJW6x5jm5kSnKVQkjvAt-A8RuiKaarCZZw at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Whoops, sorry: this is the same thing Konrad was talking about! Duh.
> Well, hopefully the link is useful.
>
> Robby
>
>
> On Mon, Sep 29, 2014 at 9:32 AM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
>> Just in case, here is one piece of related work from the PL world and
>> is probably a reasonable starting point for finding others' attempts
>> at this problem:
>>
>> http://research.microsoft.com/en-us/um/people/akenn/units/
>>
>> Robby
>>
>>
>> On Mon, Sep 29, 2014 at 3:44 AM, Konrad Hinsen
>> <konrad.hinsen at fastmail.net> wrote:
>>> Matthias Felleisen writes:
>>>
>>>  > Your message points out where gradual typing badly fails.
>>>
>>> Not just gradual typing. I am not aware of any good unit
>>> implementation in any type system, with the exception of F# and Frink
>>> whose type systems were explicitly modified to add unit checking as a
>>> special case. Dependent types should permit a good solution, but I
>>> haven't seen it done yet.
>>>
>>> The reason you need dependent types is that the product of two
>>> measures is another measure with a new unit, so you must be able to
>>> construct new types (representing units) from values. For example, a
>>> length divided by a time yields a speed. Once you can do that, scaling
>>> a unit (e.g. from meters to kilometers) becomes a special case.
>>>
>>>  > In this specific case, you have two aspects of dimensionality:
>>>  > dimension per se (I am sure there is a word for it) and the chosen
>>>  > unit to represent it.
>>>
>>> The two terms used for this distinction are in fact "dimension" and
>>> "unit".
>>>
>>>  > If someone writes (area-of-rectangle 1 [mm] 1 [km]), there is
>>>  > nothing wrong with it -- except that the type checker should insert
>>>  > a coercion from mm to m and from km to m (multiplying/dividing by
>>>  > 1,000).
>>>
>>> That's a topic of hot debate in the scientific computing community.
>>> Some argue that the type checker should consider your example as an
>>> error, and not do any implicit conversion. The motivation is that the
>>> expression you used is more likely to be a mistake than the meaningful
>>> use of expressive language, since best practices recommend to use a
>>> minimal set of units inside any piece of code.
>>>
>>> Anyway, that's a minor detail. If your type system can handle
>>> automatic conversion, then it can also handle its absence.
>>>
>>>
>>> Alexander D. Knauth writes:
>>>
>>>  > What I had in mind was for the structs to be available at run-time,
>>>  > but that ideally the optimizer could take them out for the
>>>  > intermediate operations and put them back for the final result.
>>>
>>> You are actually adding a very Racket-specific requirement to the
>>> already difficult units-as-types problem: the interplay between a
>>> typed and an untyped dialect of the same language. I agree this would
>>> be nice to have.
>>>
>>> Konrad.
>>> ____________________
>>>   Racket Users list:
>>>   http://lists.racket-lang.org/users
>
>
> End of users Digest, Vol 109, Issue 76
> **************************************