well, even though this side tracks the discussion even more, I can't help but
pitching in a few comments from a practitioner's point of view (I'm sure entire
seminars in college are dedicated to the topic of commenting, so this may or
may not be an old hat - apologies to anybody who may already
tcp doesn't care about what is sent via it. You open a TCP port (how to do this
has I believe been pointed out to you thoroughly), then you send the image as a
raw data stream. You better make sure that both sides are informed about the
length of the data - in JPG, this information is part of th
well, I don't know where the myth comes from that design and coding and
debugging can be separated, but after 20+ years as a software designer and
designer trainer in various companies ranging from a very few to several
thousand developers, I've yet to see any (commercial, I'm not talking about
Tim, I wholeheartedly agree. Scheme used to be plainly beautiful. Understand
lambda expressions, recursion and continuations, and everything else more or
less falls into place.
The Scheme part of Racket still is as cool, but the rest is a moloch. Just
syntactically understanding a Racket appli
Sorry for side tracking, I just try to understand how an excercise like
that is set up and what a "good" solution is expected to look like and why...
Good way to keep from doing real work.
Home run... :-) and end of noise on my side. Thx.
Racket Users list:
h
my Outlook wouldn't allow me to
respond all without signing my response (which somehow didn't work), so I had
to revert to a response on an earlier mail of mine, sorry.
- Original Message -
From: Matthias Felleisen
To: Rüdiger Asche
Cc: Ashley Fowler ; users@racket-l
Interesting. How does the pattern matcher do that? I tried comparing two
solutions in terms of performance (see below, group 1&4 (naive approach)
against 2&3 (matching approach)), and aside from the fact that I get somewhat
inconsistent results (when I run the test suite several times after one
Do you need to run echo.rkt under control of racket? If you compile it as a
standalone, you can use
(current-command-line-arguments)
within echo.rkt to access the vector or command line arguments.
- Original Message -
From: "Rouben Rostamian"
To:
Sent: Monday, August 20, 2012 12:42
You seem to be asking for Pascal or C/C++. Then again, is it possible that
"critical" regions of your program could be managed via finalizers and your
own memory administration? Giving up even one iota of GC soundness, sounds
like giving up all of memory soundness though it's possible I am ove
For complete precision: I meant "may" in the sense of "P |= memory is
useful" as opposed to "P |- memory is useful" -- i.e., just because a
program may not need a chunk of memory for the remainder of the
computation does not mean it is provably so. In this spirit, the word
"conservative" is a
yes it is:
(define thunk1 (lambda () (/ 100 10)))
(define thunk2 (lambda () (eval '(/ 100 10
(define iterate (lambda (ct thunk)
(if (zero? ct)
#t (begin (thunk) (iterate (- ct 1) thunk)
(time (iterate 100 thunk1))
=> cpu time: 15 real
...is there a reasonably easy way to accomplish that?
Thanks!
Racket Users list:
http://lists.racket-lang.org/users
by the way, you were absolutely right, of course. I must have been
blind on both ears and deaf on both eyes not to think about CPS in
this case. It works like a charm now!
Thanks again!
- Original Message - From: "Matthias Felleisen"
To: "Rüdiger Asche"
---
From: "Matthias Felleisen"
To: "Rüdiger Asche"
Cc: "users"
Sent: Thursday, July 05, 2012 8:06 PM
Subject: Re: [racket] again: timeouts and exceptions
1. I don't know where this prose is but it reads rather confusing.
2. If I were you, I'd use an esca
Hi there,
a few of you recommended to implement timeouting reads via
sync/timeout. That works neat, but it would be even nicer to combine
this w/ exception handling, like so:
...
((readbytetimeout)
(lambda (port)
(if (sync/timeout READTIMEOUT inport)
(read-by
al. The first person will most
probably get into trouble when the problem shows up again in the
field, and the second will get in trouble when his application not
unly doesn't run faster than before he added concurrency but locks up
in the field (frequently only in hard to track fringe c
2) Is it better to do the concurrency at the highest level possible or
at the lowest level possible. I.e. should I be processing pages
concurrently or should I go to a much lower level and only be
processing letters concurrently. Does it matter?
3) How does hyperthreading affect the number of
Sorry for being unclear. Of course I'm not asking for production level
code nor critizing your very helpful sketch.
This is more about control flow and how to realize it. To me it looks
as if the designers of the Racket TCP wrappers took the following road
(pseudo code of course):
submit
an somebody point
me to a coding strategy that takes care of all the possible cases while
still maintaining the racket charme we all love? ;-)
Thanks!
- Original Message -
From: "Neil Van Dyke"
To: "Rüdiger Asche"
Cc:
Sent: Wednesday, June 20, 2012 4:50 PM
Subject:
Hi there,
today's bug from hell might not be a Racket related issue (to me it seems more
of a Windows type of thing), but maybe somebody has already come across
something similar, so here goes:
I have a Racket application serving as a stress test against a TCP server, that
is, the Racket appli
I'm struggling with exception processing in a particular case - I'm
sure this is a trivial question with a trivial answer, but for some
reason (most probably stupidity on my part) I haven't found an answer
yet, so here goes:
I have an application that implements a communication protocol ove
quot;
To: "Rüdiger Asche"
Cc:
Sent: Saturday, June 16, 2012 6:23 AM
Subject: Re: [racket] querying the machine's system time...
I'm confused by the question. Maybe you have and old version where
'seconds->date' accepts only integers? The current version accepts a
tem
clock on a fine granularity). Thus I need absolute timing in my Racket
app...
Thanks!
- Original Message -
From: "Matthew Flatt"
To: "Rüdiger Asche"
Cc:
Sent: Saturday, June 16, 2012 6:06 AM
Subject: Re: [racket] querying the machine's system time...
I need a millisecond granularity though (or at least 100 ms) -
GetSystemTime() provides that...
Thanks!
- Original Message -
From: "Matthew Flatt"
To: "Rüdiger Asche"
Cc:
Sent: Friday, June 15, 2012 10:53 PM
Subject: Re: [racket] querying the machine's sys
Hi there,
I need to compare time events in my Racket application against output from a
third-party application that most probably uses GetsystemTime() or
GetLocalTime() for its time stamps, so I need to access those functions as well
(or other functions that contain the same information).
How
Quoting Ronald Reynolds :
I hope I'm not too much of a 'pain in the neck noobie' but what is
the short clean answer about what's going on when we
name a function as part of the definition of itself.. This seems
pretty esoteric to me. What does the system do?
I'm not sure what you mean
Hi there everybody,
I'm not sure if this hasn't been discussed before (at least didn't
find any reference in google), so apologies if this should be a dupe:
How do I set a read timeout on a port (in this case, a TCP port)? In
native socket API, it's done via setsockopt() but the socket opti
e a while; also, there is not
really a way to figure out if a port you select is in use or not).
For test purposes it works, but it appears that there is work left to be done...
- Original Message -
From: Grant Rettke
To: Rüdiger Asche
Cc: users@racket-lang.org
Sent: Sun
well I could have answered that myself (I did, eventually)... sorry for the
noise...
- Original Message -
From: "Rüdiger Asche"
To:
Sent: Friday, May 04, 2012 3:10 PM
Subject: [racket] tcp-connect and IPv6...
Hi there,
is there a way on Racket to force an outgoing TCP
Hi there,
is there a way on Racket to force an outgoing TCP connection
(tcp-coonect) to go through an IPv6 interface on a multihomed machine?
Thanks!
Racket Users list:
http://lists.racket-lang.org/users
uhm... am I mistaken, or is there one recursive call to fast-expt in a
non tail recursive position? Schouldn't that be unwound?
Quoting Stephen Bloch :
On May 2, 2012, at 11:50 PM, Deren Dohoda wrote:
Well I am sure it will try to use all the memory it can. Anyway, my
functional code can r
do it?
Thanks!
- Original Message -
From: Doug Williams
To: Rüdiger Asche
Cc: users@racket-lang.org
Sent: Saturday, April 28, 2012 10:54 PM
Subject: Re: [racket] Another PLaneTs crypto lib usage question?...
I have forked the crypto package to perform these actions for
Hi there,
I'm working with the crypto lib from PLaneT. It actually works well, so far,
thanks for the wrappers (it's a Scheme interface to OpenSSL).
My question is, how do I turn off padding, i.e. what do I have to pass (and
where) as an additional parameter to e.g.
(define dummy (encrypt ciph
likely I don't understand enough about the meaning of
init vectors, but shouldn' a strong encryption algorithm completly
garble the cipher if only one part of the input changes to prevent
attacks?...
Quoting Rüdiger Asche :
I'm doodling around with vyzo's crypto lib fro
I'm doodling around with vyzo's crypto lib from PLaneT, doing some
very rudimentary crypting and encrypting. I'm undoubtedly doing
something wrong, I just don't know what...
Here's my code (running from a directory that contains the crypto files):
(require srfi/78
"main.ss"
Hi there,
in my Racket code, I need to crypt/decrypt chunks of data using the AES
algorithm. I couldn't find anything in the docs about encryption support; did I
miss something or hasn't this been done yet? If it has, does anyone have a
pointer?
Thanks!
Racket Users list
Any suggestions for solving this problem are welcomed :)
yeah, I tried and gave up. Support for serial ports is really poor. I have a
network redirctor device which is a little box with an ethernet adapter on one
side and a DSub9 on the other; you configure it to map a serial stream 1:1 o
years when you DON'T have a job because 90% of all software will be open
source by then and the rest is expected to be free as well. There won't be
THAT many jobs in academia by then that allow you to write software and
still get paid for it from someone.
- Original Message
Thanks for this enlightening contribution!
This just reaffirms my former conviction that nothing is really free, and
I'd much rather spend my money on a good commercial product (and therebye
support the people who deserve to have their development efforts paid as
well as be entitled to profess
Hi there,
there is a chance that I can push Racket as a programming environment at a
customer's site (I'm a freelance software developer). I read the LGPL which
apparently is the basis for programming with Racket (not Racket as in "the
Programming Language family Racket" but Racket as in "the
Hi there,
when raco exe is used to create a standalone .exe and I try to run the
resulting exe from a DOS box with an empty path, the runtime support
terminates with the message
with-input-from-file: expects type as 1st argument,
given: #f;
other arguments were: #
=== context ===
embe
wow. to be able to actuallay invest development resources on stability tests
of easter eggs - well, the most positive way to look at it is that the rest
of the system is so stable that it doesn't require any more development
resources. I'll be happy to assume that that is the case! ;-)
- O
(require racket/mpair)
whether they should or shouldn't be built in... what a question... more
philosophical than technical nature, no?...
- Original Message -
From: "Chongkai Zhu"
To:
Sent: Monday, March 26, 2012 3:43 AM
Subject: [racket] why there's not mcadr mcdar and so on?
SUCCESS
11 17:13:28Racket.exe IRP_MJ_CLOSEVCP0SUCCESS
Quoting PM responder:
Try using backslashes instead of forward slashes-- ".\\com1". And
you need doubled backslashes because \ is an escape character in the
string.
On Tue, Mar 13, 2012 at 12:00 PM, Rüdiger
Hello,
Section 12.1.5 of the docs suggests that it should be possible to use
file ports for accessing serial communications, such as
(define-values (inport outport) (open-input-output-file "com1"))
That works, but
inport
#
and likewise
outport
#
which means in theory and practice t
Hi there,
why is the Zero alias replaced correctly in every form in the expression
except the case branch where it is inserted as a literal?
(require macro-debugger/stepper-text)
(expand/step-text
#'(
Hello,
in most cases you should probably simply use a regular definition like
this:
(define ONE 1)
If that definition is not exported from the module you are writing it
will probably be inlined anyway.
This doesn't appear to be true. You probably refer to this snippet of the
docs here:
x27;re
back to the initial question...
I think I should really stop thanking all of you for the amount of thought
and enthusiasm you put into these debates, so I'll just leave it at that
this is never taken for granted and always appreciated.
- Original Message -
From: "Matt
- Original Message -
From: "Matthias Felleisen"
To: "Rüdiger Asche"
Cc: "Stephen Bloch" ; "users Users"
Sent: Friday, March 09, 2012 5:28 PM
Subject: Re: [racket] eginner's question on elementary textual
replacement...
On Mar 9,
True, there is no need for any particular way of representing the states as
long as there is some way to test two things for equality. However, unless
the compiler can be told to disregard the internal representation of the
symbol, it won't eat up lookup time but representation space - ie if I
Hi there,
#1: My graduate thesis (in 1988) was an implementation of Scheme. I do
feel reasonably comfortable with tail recursion, continuations,
closures and the "basics," even the basic notion of hygienic macros
(which Eugene Kohlbecker had just finished his doctorate on when I
studied S
cement of every occurrence of
ONE by 1 before evaluation time?...
Thanks again!
Quoting Neil Van Dyke :
Rüdiger Asche wrote at 03/09/2012 04:39 AM:
(let-syntax [(ONE 1)]
((lambda (x) (+ ONE x))
2))
won't work... so how do I do it?
If you really want to do this, here are two ways
Hi there,
I need a counterpart for the C #define statement, meaning a way to
textually replace every instance of id at preprocessor time with its
defined value, as in
#define ONE 1
unsigned int addone(unsigned int theArg)
{
return (theArg + ONE);
}
I understand that Scheme's macro sy
Hi there,
does anybody have sample code for accessing serial communications on
Racket, meaning a) how to open and close a port, b) how to configure
it (setting and retrieving parameters such as baudrate, handshaking
etc) and c) how to perform I/O on it? FWIW, this is Racket on Windows.
Th
Jon's elaboration along with the paper mentioned here puts many open
questions in place. Thank you all very much!
Without (yet) having understood the concept in detail, I was wondering if
it's fair to say that phases add another dimension to computing, denoting
decision making over different p
e and ultra fast response!
- Original Message -
From: "Danny Yoo"
To: "Rüdiger Asche"
Cc: "Racket mailing list"
Sent: Thursday, March 01, 2012 12:21 AM
Subject: Re: [racket] Splitting Racket source code by scope?
Hi Rüdiger,
The top of all four files should have
#l
You wrote:
---
As Matthias mentions, you can formally link together "units" together.
Units are Racket's dependency-injection component framework. You can
read documentation about them here:
http://docs.racket-lang
al Message -
From: "Matthias Felleisen"
To: "Rüdiger Asche"
Cc: "Danny Yoo" ;
Sent: Monday, February 27, 2012 11:44 PM
Subject: Re: [racket] Splitting Racket source code by scope?
On Feb 27, 2012, at 5:33 PM, Rüdiger Asche wrote:
Thanks again - but there is som
) at:
# in: (include "othersuch.scs")) ? I
read the docs to use current-directory consistently on load and include?
- Original Message -
From: "Danny Yoo"
To: "Rüdiger Asche"
Cc:
Sent: Monday, February 27, 2012 6:22 PM
Subject: Re: [racket] Splitting Racke
I'd like to split the components of my Racket project into multiple
files according to this structure:
contents of file1:
(letrec ((id1 body1)
...
...
)
(main execution body using id1, idx, idy...)
)
contents of file2:
(idx bodyx)
(id
On my machine at work (admitteldly, older - 512M RAM, Windows XP SP2), DrRacket
crashes predictably, even when I don't run any code of mine - it's enough to
run the macro stepper on a reasonably complex expression. I do attribute this
to low memory conditions and found that Dr.Racket claims abou
sorry for the noise, I obviously misread the documentation. Thanks for the
answers and polite reactions.
- Original Message -
From: "Robby Findler"
To: "Rüdiger Asche"
Cc:
Sent: Friday, February 17, 2012 3:22 PM
Subject: Re: [racket] thread execution granula
according to the Racket docs, the smallest amount of time a thread can
be put to sleep is 1 second. I need a finer granularity than that...
if I had access to the thread priority, I might just have the thread
poll the timer on low priority, but I haven't found a way to do that.
What I need
Am I having hallucinations, or does Dr. Racket come up with a heart shaped
banner logo today with anybody else? Is this an easter egg of sorts? (well
of course I KNOW it's V-day, but I didn't know that Dr. Racket knows about
these things...)
Racket Users list:
http://lis
To get the best suggestions on alternative data structures you should
say a little more about wha your program does and thus needs. However
if all you're interested in is adding to the back and removing from
the front, that is a queue, you can implement one using two lists
without mutating the li
Hi there,
My application makes heavy use of potentially very large lists and
needs to access them as efficiently as possible which is why I wrote
my own list manager. Basically the "root" of the list representation
is a mutable pair whose mcar points to the head of an mlist and whose
mcdr
Thanks for the fast and on-the-spot response!
Is there a way to run the preprocessor only so that I can see what code that
construction expands to before being passed to the read-eval loop?
- Original Message -
From: "Matthias Felleisen"
To: "Rüdiger Asche"
Hi there,
I'm trying to get a grip on macros. Here is a very simple Racket
expression (1):
(letrec [(a 2)
(b 3)
(afn (lambda (x) (+ x a)))
(bfn (lambda (x) (+ x b)))]
(afn (bfn 2)))
Now I need a syntactic abstraction for afn and bfn. The following will
do in
(et-displayed 12 4)
)
Quoting Rüdiger Asche :
Hello, I'm trying to brush up on my scheme/racket, and here's something
I came across when trying to rework the issue of continuations - I'm
sure this qualifies as a beginner's question, so sorry for probably
asking a stupid
Hello, I'm trying to brush up on my scheme/racket, and here's
something I came across when trying to rework the issue of
continuations - I'm sure this qualifies as a beginner's question, so
sorry for probably asking a stupid question - I promise to ask better
ones in the future:
Consider
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