I’m a little confused here, to me it looks like the second contract violation
is completely different from the first one.
You were expecting `foo` to raise a contract violation but in your executable
example it appears that contract violation is being raised by the `build-path`
function not `fo
Something like the following program:
#lang racket
(module foomod racket
(provide foo)
(define/contract (foo arg) (-> string? #t) #t))
(require 'foomod)
(provide (contract-out (foo (-> non-empty-string? #t
On Tuesday, September 4, 2018 at 9:00:06 PM UTC-4, David K. Storrs wrote:
>
>
What about reproviding foo and using contract-out to wrap foo in a new
contract?
On Tuesday, September 4, 2018 at 9:00:06 PM UTC-4, David K. Storrs wrote:
>
>
>
> On Tue, Sep 4, 2018 at 8:55 PM, Matthew Butterick > wrote:
>
>>
>> On Sep 4, 2018, at 3:54 PM, David Storrs > > wrote:
>>
>> Say
I was an attendee of Racket Summer School 2018 where we covered
syntax-parse extensively.
The lecture plans and problem assignments are still available online and
they together comprise a good tutorial for syntax-parse and language design
principles.
I encourage you to give it a try!
https://
Would it be possible to adjust the readtable to replace "→" with "->" ?
On Wednesday, May 16, 2018 at 10:32:43 AM UTC-4, Andrew Kent wrote:
>
> `racket/string` needs to be required _for syntax_ in order to work in the
> suggested way (because it's bindings are needed at compile time).
>
> The f
My guess the problem is
(define imleftname
#"./tsukubaleft.jpg")
You're using a relative path to the jpg file which may be valid wherever
your script file is located but DrRacket is probably starting up with a
different working directory and the relative path is not resolving
successfully.
As an aside, vectors are intended to be a constant-time access data
structure. Lists aren't so it won't make sense to build vectors on top of
lists which would make for non-constant slot access times.
On Monday, March 26, 2018 at 4:13:02 PM UTC-4, lysseus wrote:
>
>
>
> > On Mar 26, 2018, at 11
On Friday, February 23, 2018 at 11:08:23 AM UTC-5, David K. Storrs wrote:
>
>
> On Thu, Feb 22, 2018 at 11:14 AM, Alexander McLin > wrote:
>
>> As one of those who have been following RISC-V progress for several years
>> and also interested in seeing Racket being po
As one of those who have been following RISC-V progress for several years
and also interested in seeing Racket being ported to that architecture I
want to drop a note to let you know you have my support!
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Your interactive plot looks wonderful and would be a good replacement for
some of R's statistical graphing features. I'm excited you're making this
valuable contribution to Racket.
I did noticed something in your documentation at
https://alex-hhh.github.io/2018/02/interactive-overlays-with-the-
Thanks all for your inputs.
I tried `with-intercepted-logged` before though it didn't solve all of my
issues, though as Robby mentioned, my code probably isn't accurately
capturing all of the start and exit nuances my need reflect, I'll need to
think more about the big picture to do a better jo
ust
using old-fashioned `println`s
Thank you for your suggestions.
Alexander McLin
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All three approaches you outlined are viable but web service is easiest to
set up.
>From what you described, it seems it would be a low-performance use for
Racket and only simple data structures will be passed back and forth on an
infrequent basis. Web service would be a good fit for that.
Ou
On Wednesday, January 24, 2018 at 5:54:44 PM UTC-5, Alexis King wrote:
>
> Based on your question, why not just use dynamic-wind in combination
> with with-handlers? Just keep in mind that the post-thunk could be
> called multiple times if there is a continuation jump into value-thunk,
> so you
I have a with-handlers expression which handles several exceptions
appropriately and raises user-error exceptions, I have some additional code
I'd like to be executed after the exception have been handled, analogous to
dyanmic-wind's post-thunk argument or like the finally clause of a
conventio
I don't have much to add but wanted to note that the problem appears to be
in rendering grengor's documentation. The package itself may be installed
fine, just not its associated documentation. You can test to verify if
package is installed by querying via raco pkg or just requiring gregor in a
This is quite a timely post. I had been looking into using a JSON schema
validation C library and using FFI to hook into that for my projects.
I'll give your new package a try!
Thank you for making it available Jesse.
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Yes, you can use DrRacket to debug the file at
collects/db/private/sqlite3/connection.rkt. That one is likely the most
relevant one for you.
Alternatively, you could wait till Racket 6.10 is released which is very soon I
think. The bug fixes to the db library might reveal the correct error mess
I tried query-exec on those SQL strings you posted on gist on my local copy of
Racket 6.8 with an in-memory SQLite3 db and it worked fine.
I'm not sure what's causing your issue. What version of Racket and SQLite3 are
you running on your machine? Is it Windows, Linux, or Mac OSX?
> https://gi
One more thing for you to check, make sure there's no trailing whitespace after
the end of your statement's terminating semi-colon, that will also trigger the
`multiple statements given` error. That bug has been also fixed in the current
repository.
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It appears you're giving to `query-exec` a string consisting of two statements;
the create table and insert into statements. `query-exec` only supports
executing one statement at a time.
If you break your two statements up into two strings and call `query-exec` on
each one, it should work.
--
Consider using the following function
https://docs.racket-lang.org/reference/pairs.html?q=memq#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._memq%29%29
It's helpful to sketch out the general steps you'd need to be able to carry out
the procedure to solve the problem.
My quick sketch would
FYI, the misleading "multiple statements given" error has been fixed in the
racket master branch and correct syntax error message is now being raised.
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Thank you Alex, your code looks comprehensive and ought cover my use case.
Appreciate your sharing!
Best,
Alexander
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`db` library doesn't seem to provide support for executing batch statements
against a database. I'm trying to initialize and create an in-memory SQLite3
database using a SQL schema file. `query-exec` and its friends only support
executing single SQL statements.
Reading documentation isn't show
While I have no strong preferences for whether it would be better to allow
end-users determine what tags to apply as opposed to automatic system tags, it
might be more effective to make provisions for special tags to be supported in
info.rkt and have the catalog automatically read those tags if
All of your suggestions are great and get my vote.
To elaborate on the raco tag, it should list all the commands *and* subcommands.
Example:
pkg package
tag: raco: pkg install, pkg update, pkg remove, etc.
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First of all, I wish to express my appreciation for such a beautifully designed
package catalog site located at pkgs.racket-lang.org.
I was wondering if we could add a special search term category or tag that list
all available raco commands that packages may install?
For example, when building
> Indeed. What would be such classical papers from your field?
One paper I have in mind is Hodgkin & Huxley's paper published in 1952 where
they first wrote down the equations describing the membrane voltage of the
giant squid axon.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392413/pdf/jphys
Leandro,
Your article comes at a good time for me because I received my copy of
"Semantics Engineering with PLT Redex" last week and am preparing to start
studying it. I thought your examples are a nice exposition of the complex ideas
that go into selecting features a programming language needs
The error message is unclear but I believe SQLite do not support parameters for
PRAGMA statements.
The SQLite documentation at http://www.sqlite.org/lang_expr.html#varparam
specifically says parameters are supported by expressions. PRAGMA statements
are not expressions.
If you examine the SQ
This looks quite promising, I'm liking the progress and examples so far. The
idea of using the same notation to express both equations and algorithms
excites me. It would certainly make it easier to write down and analyze
algorithms implementing a set of model equations in a language independent
You need to compile Racket from source to generate the .lib file, it is not
distributed with the installation.
You need to make sure the source is the same version as your installed Racket
and it is compiled targeting the same bit architecture as the installed Racket
version. Then copy the gene
I understand where you're coming from. My organization is flexible and isn't
ideologically committed to one particular platform. Microsoft's community
promise is just that, a promise. It can be changed or revoked at any time in
the future.
I've been encouraging adoption of open system practices
Thank you Matthias for the historical information, it was interesting to learn
that a porting project was sponsored by Microsoft in .NET's early days. Were
any papers describing the efforts published?
Porting Racket to .NET definitely is ambitious and as you have said, it seems
unlikely .NET ha
oo much impedance
mismatch.
Any design ideas or suggestions are very much welcome.
Best,
Alexander McLin
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I remember those classes as a student, to be honest I didn't really actually
started to learn till after I'd left undergraduate.
Don't get me wrong, I know how frustrating syntax/semantics nuances can be.
I've been reflecting on the idea of existential keywords the past couple days
and have rea
se in the keyword grammar when all other keyword cases are
allowed to assume arbitrary values.
Aλexander
On Sunday, November 22, 2015 at 12:08:49 PM UTC-5, Alexander McLin wrote:
> I don't really have a horse in this race. My position is very similar to
> Alexis which is why I di
I don't really have a horse in this race. My position is very similar to Alexis
which is why I didn't vote in the poll too. When I first arrived to Racket the
#: syntax made me go "what in the world?" Since then I've grown to appreciate
the reasoning behind the deliberate eye catching keyword sy
No question, this would be a challenging project.
Do a clean room fresh implementation or provide full Emacs Lisp compatibility?
Would it make sense to consider doing a strict subset of Emacs Lisp, with
sufficiently flexibility to allow popular extensions run while leaving others
behind?
Commo
On Wednesday, July 1, 2015 at 7:07:03 AM UTC-4, AJ Campbell wrote:
> JSON is probably going to be the go-to format to send/receive renderable 3D
> packets. The thought of doing it with XML makes me feel ill. I'm sure Racket
> can handle JSON data (it very well might already for all I know), but
Hello Darren,
May I offer this point of view regarding tautological tests. They are useful
for checking if your assumptions are consistent and they stay that way over
multiple iterations of design modifications.
Personally I've found keeping a list of assumptions only in my head is a recipe
fo
it so I
don't know whether it works or not but it's worth a look.
> On Nov 26, 2014, at 8:00 AM, Catonano wrote:
>
>
>
> 2014-11-26 13:17 GMT+01:00 Alexander McLin :
>> The square function is also defined in earlier SICP sections so I would
>> recommend you mai
The square function is also defined in earlier SICP sections so I would
recommend you maintain a running file of all functions SICP defines so you can
refer back to them easily.
> On Nov 26, 2014, at 5:37 AM, Catonano wrote:
>
> Hello
>
> I understand that this is not the first time someon
n the -> form which is the ->* contract.
On Fri, Oct 3, 2014 at 10:55 PM, Alexander McLin
wrote:
> Actually I wasn't quite ready to move on.
>
> When I apply (curve 3) where (define curve (cubic-bezier a b) a and b are
> bezier-control-point?
&g
as passed and — at least for me — cubic-bezier is long since gone, and
thus out of mind.
Alexander McLin
On Fri, Oct 3, 2014 at 9:59 PM, Alexander McLin
wrote:
> Good evening Mathias,
>
> After studying your program and mine, and running various permutations, I
> understand whe
gt; (define b (bezier-control-point 0.3 9.0))
>
> ((cubic-bezier a b)
> ;; a contract violation because i isn't comparable
> (sqrt -1)))
>
>
> drracket or raco test file.rkt will show contract errors.
>
>
>
>
> On Oct 2, 2014, at 1:50 PM, Alexander McLin
-
> ;; run program run
> (require 'client)
>
> I assume you want to see other violations. Can you explain with this
> example w/o going into Bezier?
> (I just know enough about Bezier to draw curve
d inputs to cubic-bezier's value.
How can I attach a more complex contract to cubic-bezier's value?
Thank you
Alexander McLin
Racket Users list:
http://lists.racket-lang.org/users
Good grief, was it necessary to spam the list with your requests? You could
have just sent one email instead of replying to like 20 different threads?
And it would have been nice if you'd read the basic instructions which
tells you exactly how to unsubscribe yourself without flooding my inbox.
On
Thank you for this information. I had been trying to figure out how to test
contracts from within a module+ only to give up and move my test cases to a
different file.
I think this reinforces that I should be asking more questions on the mailing
list.
Alexander McLin
> On Aug 26, 2014,
This is fun! I loved how my screen would shake and flicker each time I get
slammed by a fire volley. Certainly got my adrenaline pumping.
On Sat, Jul 12, 2014 at 12:01 PM, David Vanderson wrote:
> For the past 6 months my hobby has been writing the beginnings of a
> lan-party game in Racket:
>
Thanks!
On Fri, May 9, 2014 at 11:33 AM, David Van Horn wrote:
> On 5/9/14, 11:29 AM, Alexander McLin wrote:
> > Do you mind expanding on what MTWT stands for? I'm not familiar with this
> > paper and am curious.
>
> Macros that Work Together
> http://www.eecs
Do you mind expanding on what MTWT stands for? I'm not familiar with this
paper and am curious.
On Thu, May 8, 2014 at 6:20 PM, John Clements wrote:
>
> On May 8, 2014, at 3:00 PM, Ryan Culpepper wrote:
>
> > IIRC, the typesetting of environment extension might suggest replacement
> in a mappin
Looking forward to checking out your Pollen package in more detail, just
wanted to add that after reading your original email and following the
links, I eventually discovered myself losing a hour or two reading your
typographical book. Very nicely written and I look forward to studying it
more care
I see, thanks for the detailed explanation. I understand the issue is whether
the cost associated with cons checking arguments prior to creating the pair is
acceptable or not but truly if cons is checking for list? by whether a bit is
set or not, wouldn't that be negligible compared to the cost
I'm joining in this thread because I'm now wondering about the same questions.
It seems to me that if a list is created via list or make-list then the bits
should have been set on the car of the new list, so all the list predicates
have to do is check the first element in O(1) time.
Likewise co
Daniel, I think it'll be worthwhile to direct your attention to this blog
entry which goes into more details about why mutable pairs were removed in
the first place.
http://blog.racket-lang.org/2007/11/getting-rid-of-set-car-and-set-cdr.html
On Wed, Mar 5, 2014 at 4:15 PM, Jens Axel Søgaard wrot
Unfortunately I don't think I have enough time to be a serious contributing
developer here, but the goals of this project brought to mind another
project I had studied some time ago with similar goals of creating a secure
browser based on a capability-based security model.
The project team used a
Racket is truely a great and cleaner Lisp. It's carved out its own path
that I find quite attractive and am enjoying my forays into Racket.
I would recommend you just get started with The Little Schemer to get a
taste, move on to How To Design Programs. There is a Coursera course that
uses HTDP, a
o the Scheme-79 paper yet (thanks for the reference by
> the way!).
>
>> On Oct 19, 2013, at 1:35 PM, Alexander McLin wrote:
>> I'd be interested in hearing how it's going!
>>
>> Just curious, are you reusing ideas from Scheme-79, or starting off in a
I'd be interested in hearing how it's going!
Just curious, are you reusing ideas from Scheme-79, or starting off in an
entirely different direction? From your original email, I assume you're using
JOP as a springing board?
Alex
> On Oct 19, 2013, at 4:32 AM, Petr Samarin wrote:
>
> First I w
Thank you for the illuminating primer, Matt. I hadn't realized that it was
such a questionable term.
On Wed, Aug 28, 2013 at 12:54 PM, Matthias Felleisen
wrote:
>
> On Aug 28, 2013, at 12:33 PM, Grant Rettke wrote:
>
> > On Wed, Aug 28, 2013 at 11:04 PM, Matthias Felleisen
> > wrote:
> >> For
ew" for Matthew Flatt, the CEO of PLT Design, Inc, creator of
> Racket, and ruler of the kingdom
> -- "Matthias" for me, which yes, is a form of Matthew (used in Germanic
> and Hispanic contexts with various spellings).
>
>
>
>
>
>
> On Aug 28, 2013, at 1
I would like to understand this some more.
My understanding of applicative order is also connected with normal order,
I thought applicative order just means that all arguments given to a
procedure are always evaluated before the procedure is applied, the
left-right or right-left detail is irreleva
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