Hi,
this is my first posting to the racket users list.
Is this the right place to post questions of a
very beginner to racket programming (and lispy
programming)?
Best regards,
Meino
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Hi,
(I am still a newbie ... )
If I remember one rule of functional programming
correctly, it says:
Instead of changeing data - create new data.
Suppose I have a list of list. Each "sublist" is
made of a greater amount (but identical count) of
exact numbers (integers).
I want to process the
Hi,
I have installed racket on my Android tablet.
For this I have the device rooted
and installed a chrooted Archlinux,
which in turn provides the prebuild
racket-package 6.6.
By the way: The tablet has a x86 iIntel CPU
but nothing "big iron"-like. About 400MB
free RAM is available.
BUT:
When I i
Hi,
A more general question:
I am no native english speaker and a newbie when it
comes to Racker/Lisp/Functional programming.
Suppose I want the name of a function or functionality
(like this genious 'apply map' algorithm to hurry through
a list of lists) - how/where can I search for it if I
can
Asumu Takikawa [16-10-23 18:12]:
> Hi Meino,
>
> On 2016-10-23 11:09:48 +0200, meino.cra...@gmx.de wrote:
> > It there any way to tell raco what kind
> > of doc processing is wanted and what don't?
>
> In addition to Daniel's answer, there is a temporary workaround you can do
> which
> is to in
Hi,
I want to create a list of random strings.
For that I have created a function, which returns a string
of random length and random contents.
Then I used
make-list n (make-random-string)
to create that listand get back a list filled with n
identical strings.
h...
make-list calls
Hi,
after putting Racket on my desktop Linux box and on my tablet
(ARCHLinux chroot, x86 CPU) I want to put Racket on my Orange PI
PC (which is a Raspberry Pi inspired SoC-Computer). This Orange
Pi PC runs a " ARMBIAN Debian GNU/Linux 8 (jessie) 3.4.112-sun8i"
The CPU is (according to /proc/cpuing
Hi Matthew,
thanks fpr your reply! :)
I received a recipe how to modify the configuration
of the ARMBIAN to pull from "unstable" source.
"Unstable" includes racket 6.6 (and hopfully 6.7
soon) -- I think those "unstable" sources are of
Raspbian... :)
Still downloading/updateingfingers crossed.
Matthew Flatt [16-10-28 05:04]:
> If ARMBIAN and Raspbian are compatible, then you could try the Utah
> snapshot site's Raspbian build:
>
> http://www.cs.utah.edu/plt/snapshots/
>
> At Fri, 28 Oct 2016 03:21:49 +0200, meino.cra...@gmx.de wrote:
> > Hi,
> >
> > after putting Racket on my deskt
Hi,
currently I am still doing old-school "printf()-debugging", knowing
that it's '(print arg)' rather than 'printf( fmt, val,...);". :)
Since my program reads a bigger textfile of shortwave broadcasters,
their frequencies, on-air times, etc, reformats the whole thing
and (currently only to p
Hi,
...still improving my shortwave-broadcaster-dumper... :)
I have a list with sublists of strings, which I want to concatenate.
Each sublist shall form one line of output.
I tried 'string-append', but this gives me something like this
(excerpt):
"189RikisutvarpidRas1+2-24001234567Icelandic"
Hi Ken,
thanks for your reply ! :)
The problem is much "simpler"... :)
You wrote the whole logic to dig into the strings in the sublists in
the big list.
That's already done and working
I am in search for doing this
(string-join '( "a" "b" "c") " " ) ;; ( "a" "b" "c") is the sublist
but in t
Hi Stephen,
thanks for yoru reply ! ::)
At the certain point of the program I get
a list as parameter 'lst', which contains
the sublists of strings. I wrote this
function:
(define (to-txt lst)
(if (empty? lst)
lst
(let ((line (car lst)))
(begin
(displayln (apply string-
Hi all,
...think, I have to apologize
I screwed it upit is a language (spoke one...not "programming" )
thing:
I read "List of strings" which in german is "Liste von Zeichenketten".
THIS expression means this:
"A" "B" "C"
(for example).
This applied to string-join in a germenglish head for
Hi,
While using racket 6.6 I installed the package 'cvs-reading' in $HOME
with 'raco pkg install cvs-reading' as me (not as root).
Now, after updateing to racket 6.7, this package cannot longer
be 'require'd :
> (require cvs-reading)
; readline-input:1:9: collection not found
; for module path:
Hi Jack,
thanks fpr your reply ! :)
I tried that with this script (copied from the docs, "/bin/env racket
replace by the actually path to racket):
#!/usr/local/bin/racket; \
#lang scripty ; | script preamble
#:dependencies '("cvs-read
Hi John,
from my racket 6.6 installation ($HOME):
:user/.racket>l
total 20
drwxr-xr-x 5 user users 4096 2016-10-21 05:25 6.6
drwxr-xr-x 5 user users 4096 2016-10-30 06:21 6.7
drwxr-xr-x 2 user users 4096 2016-10-30 06:21 download-cache
-rw-r--r-- 1 user users 5254 2016-10-30 06:25 racket-prefs.
Hi John,
thanks for your reply! :)
the only cause for makeing my life "terrible" at that moment
was myself and the lack of coffee
I confused csv with cvs
No need to apologize for anything, John!!!
I am the only person, who needs to apologize...you understand
everything correctly...
Only
Hi Matthew,
thanks for your reply ! :)
The problem was: That print loop creates a lot of #\spaces before
dumping the 7000+ of data lines. And there was no #\n between the
lines.
In vim I saw "nothing" (not exspecting that there were valid
data after those spaces).
On the console this block of s
Hi Georgs,
thanks for your reply! :)
NICE!
Even here, in the non-imperative, functional world, "C" leaves
its footprints in the snow... :
Cheers,
Meino
George Neuner [16-10-30 10:08]:
> On Sat, 29 Oct 2016 13:45:43 +0200,
> meino.cra...@gmx.de wrote:
>
> >currently I am still doing old
Hi,
(still fiddling around with those data of shortwave broadcasters and
their schedules...)
The data in question consists of 7400 lines of 16 fields each. Not all
fields are filled in eacht line. The already existing code reads the
data into lists of sublists of 16 fields/items.
I want to prepa
Hi Matthias,
thanks for your reply ! :)
H...your are asking a newbie, what not linear in processing
lists...h... ;)
I read somewhere on the net, that - in opposite to vectors --
processing lists is not linear. I /think/ (read: dont know for
sure), that searching needs extra time to jump
Hi,
I have a lng list of something. And I have a recursive serach
function to crawl down the list and search for a previously determined
item.
When found, the search processes stops and returns that item of the
list.
In a second step, I want to process the list starting with that
certain item
Hi Jon,
thanks for reply! :)
My plan was, to return only one element from that list and
possibly some extra informations and pass that to the processing
function so it could right jump onto that train...
Is that possible?
Cheers
Meino
Jon Zeppieri [16-11-01 04:20]:
> On Mon, Oct 31, 2016 a
Hi George,
thanks for your reply! :)
THAT HELPS!
Thanks for the look inside of racket!
Cheers
Meino
George Neuner [16-11-01 05:20]:
> On Tue, 1 Nov 2016 04:28:26 +0100,
> meino.cra...@gmx.de wrote:
>
> >
> >Hi Jon,
> >
> >thanks for reply! :)
> >
> >My plan was, to return only one element f
Hi,
not a Racket thing...
>From all threads I started or posted to I receive each mail twice.
I am using "mutt", the lInux mail client, to write and compose mails.
Mutt knows about mailinglists. Normally "r"eplaying to a posting
of a mailinglist, mutt asked "Reply tp list? [yes]/no" and hitting
George Neuner [16-11-01 18:47]:
> On Tue, 1 Nov 2016 09:24:54 -0400, David Storrs
> wrote:
>
> >I also have been getting [duplicate posts], and I use GMail.
> >
> >I suspect part of the problem is that when I hit "Reply All" to this
> >message, it was going to send to "Meino + list" and I had to
Hi Ken,
thanks for your reply ! :)
...sorry, I forgot to mention a certain aspect:
The list begins with unwanted items and after that,
all following items are wanted.
Finding the first wanted item means: The search is over
now, from here happiness will start! :)
"Filter"ing means to crawl down th
Hi Vincent,
thanks for your info! :)
...but unfortunately I cannot find find-it in
the docs...
Cheers
Meino
Vincent St-Amour [16-11-01 18:47]:
> FWIW, your `find-it` is a thin wrapper over `memf` from `racket/base`.
>
> Vincent
>
>
>
> On Tue, 01 Nov 2016 05:06:47 +0100,
> George Neuner
George Neuner [16-11-01 18:47]:
> On Tue, 01 Nov 2016 06:47:24 +0100, Vincent St-Amour
> wrote:
>
> >FWIW, your `find-it` is a thin wrapper over `memf` from `racket/base`.
> >
> >Vincent
>
> Sort of. In a roundabout way, the OP also asked about how to return
> multiple values from a function.
'John Clements' via Racket Users [16-11-01
18:47]:
>
> > On Nov 1, 2016, at 8:02 AM, David Storrs wrote:
> >
> ...
> > > Is it possible to jump right into a list at a certain item of
> > > the list and to start processing there?
> >
> > Yes. What you want is list-ref
> >
> > (define my-lis
Hi David,
thanks for your...:) DOCUMENTATION PROJECT :).!!!
Whow!
Now I have a lot to read!
Cheers
Meino
David Storrs [16-11-01 18:47]:
> Hi Meino,
>
> Good news! There are built-ins that will do almost all of this for you:
>
> On Mon, Oct 31, 2016 at 10:53 PM, wrote:
> > Hi,
> >
>
Hi Jon,
thank you for your mind reading! :::)))
Exactly!
Now I know, that racket passes references under the hood
and the world is getting a better place again.
Cheers
Meino
Jon Zeppieri [16-11-01 04:40]:
> On Mon, Oct 31, 2016 at 11:28 PM, wrote:
>
> >
> > Hi Jon,
> >
> > thanks for rep
Hi,
when using the search function for the Racket-docs
with string-trim I found:
-
Trims the input str by removing prefix and suffix sep, which defaults to
whitespace. A string sep is matched literally (as opposed to being used as a
regular expression).
Use #:left? #f or #:righ
Hi,
(this is by no means any critism against Racket!)
I have to break down input from textfiles in lists. Due to
missing formatting symbols like ";" (csv) I have do it more
"analogous". ;)
It can be done by regex and it can be done by line splitting,
procesing the results (removing superflous wh
Hi David,
thanks for your reply! :)
...unfortunatelu this wpuld imply to implement both solution
correctly and compare them.
I asked here on the mailinglist fpr the better solution just
to avoid that... ;)
Cheers
Meino
David Storrs [16-11-04 17:36]:
> That's a good question -- I don't know
Hi George,
thanks for your reply! :)
I know Perl and its regexp quite well...so I will
go for the regexified solution first.
But...I fear I have to sort my brain first. I played around
a little with regex-match and friends...and often I dont
understand the results...
Cheers
Meino
George Neu
Hi,
Normally I would tend to think, that I am
quite familiar with regex and their usage
(background: UNIX?Linux, sed, vi/vim, Perl...)
Then I played a little with regex-match...and
I have to go to school again..,,
>From the Racket guide:
> (regexp-match #rx"([a-z ]+;)*" "lather; rinse; repeat;"
Hi Jens,
thanks for your reply! :)
...hmmm...I /think/ I understand the mechanism now...but
if it is as it seems to be...I run into another problem.
Suppose your have a long line of character with groups
of certain chararcter and random caharcters in between.
Something like this
SHDKJSHKDAHSKJD
Hi David,
thanks for your reply ! :)
SUPER! THAT helps!
Is this kinda "pattern", that
if 'function' does something once, there is a
'function*' that does the same thing multiple times?
Cheers
Meino
David Storrs [16-11-05 14:37]:
> (regexp-match* #px"(AA.+?AA)" str)
>
>
> regexp-match*
Hi,
I put Racket on different computers and tablets.
So my 7" tablet receives a copy fo Racket :)
But:
The pdfs of the documentation
have a wide blank border and a ratio aspect,
which is different of that of the tablet.
When viewing the pdfs with mudf, it (mupdf)
tries to disply "the whole page
Hi David,
thanks for your reply! :)
I installed pdfcrop and processd "reference.pdf" with it like so:
pdfcrop --verbose reference.pdf reference.cropped.pdf
The result was without any margin (this was only a testrun!):
-rw-r--r-- 1 mccramer users 3070399 2016-11-06 04:30 reference.pdf
-rw-r--r-
For me it is vim with tslime.
Tim Jervis [16-11-07 02:48]:
> Emacs (Aquamacs) (with racket-mode and Paredit) for me, with occasional
> DrRacket use for rare debugging, especially Macros.
>
> Tim
>
> > On 5 Nov 2016, at 13:14, Ken MacKenzie wrote:
> >
> > So as much as I know there is much l
Hi,
>From a list of items I want to select certain items. The selecting
criterion is the index (nth item).
>From this list and from articles on the internet I think that indexing
a list and processing a list by index is not a good idea -- at least
it seems not to be very "lisp-y" or "racket-y"...
Hi Matthias,
thanks for your reply ! :)
I am learning a lot especially from examples like you gave me!
:)
Cheers
Meino
Matthias Felleisen [16-11-09 04:04]:
>
> > On Nov 8, 2016, at 9:36 PM, meino.cra...@gmx.de wrote:
> >
> > Hi,
> >
> > From a list of items I want to select certain ite
Asumu Takikawa [16-10-23 18:12]:
> Hi Meino,
>
> On 2016-10-23 11:09:48 +0200, meino.cra...@gmx.de wrote:
> > It there any way to tell raco what kind
> > of doc processing is wanted and what don't?
>
> In addition to Daniel's answer, there is a temporary workaround you can do
> which
> is to in
Hi,
I have a list of sublists. Some of the sublists are empty.
The list should be processed recursevly and the resulting
list should no longer contain empty sublists.
The code I have so far looks like:
(define (step-through-list lst)
(if (empty? lst)
lst
(cons (process-sublist (car l
Hi John,
thank you for your reply ! :)
...no, not a homework...
I want to teach myself some racket and hope 'to get it' finally...
Since I am no native speaker I have the deficulty to search for
things, which names I dont know...
One example of my code is:
(define (trim-list lst)
(if (empty?
Hi David,
thanks for the reply and the link! :)
I have a list of sublist, which I want to process recursively.
Some sublists are empty, some are filled.
The typical pattern is (as far as I know)
(define (process-list lst)
(cons (do-somthing-with-sublist (car lst)) (process-lst (car lst))
Hi Justin,
thanks for reply and the code! :)
Cheers
Meino
Justin Zamora [16-11-17 04:02]:
> I think you are looking for something like this:
>
> #lang racket
>
> (require test-engine/racket-tests)
>
> (define (remove-empty-lists lst)
> (cond
> [(null? lst) '()] ; Check for end of list
Hi,
is there a racket function, which shuffles a list of items
based on a seed value...that is: Same seed value results in
same shuffle results?
Cheers
Meino
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Daniel Feltey [16-12-02 09:28]:
> I think something like this works:
>
> ;; shuffle/seed : list? integer -> list?
> (define (shuffle/seed lst seed)
> (random-seed seed)
> (shuffle lst))
>
> > (define a-list (list 1 2 3 4 5 6 7 8 9 10))
> > (shuffle/seed a-list 0)
> '(3 4 9 8 5 1 10 7 6 2)
>
Hi Gustavo,
oh YEAH - WHOW...what a *MACHINE* ! :) 8)
Thanks a lot!
Cheers
Meino
Gustavo Massaccesi [16-12-03 03:18]:
> I suggest to use the current-pseudo-random-generator, because otherwise the
> shuffle/seed will change globally the random sequence of all the program.
> For example:
>
>
Hi,
to create html/pdf-documentation from xml/ascii-sources I want to
use racket/scribble/texinfo.
Is it a good idea? Is it possible? Or is it a academic approach only (read:
pain)? ;)
Thanks a lot for any help!
Cheers
Meino
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