Re: [racket-users] Calling function with Scribble text as argument(s)

[Hendrik Boom]

On Tue, Jul 30, 2019 at 04:04:38PM -0400, Ben Greenman wrote:
> > Now for the next problem.  If I @include-section, an occurrence of
> > redtext in the included section is recognised as an unbound identifier.
> > Evidently I need to say something to get included sections to inherit
> > bindings fro the main file.
> 
> `include-section` is much closer to Racket's `require` than TeX's `include`

I see.

So the included section has to do its own definition of redtext, or require
it from a common source.

-- hendrik

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Re: [racket-users] Re: Racket v7.3.0.900 is available for testing

[Matthew Flatt]

The latest release candidate at pre-release.racket-lang.org fixes this
problem.

Thanks again!

At Fri, 26 Jul 2019 22:58:38 -0700 (PDT), Alex Harsanyi wrote:
> I can install the windows version of Racket CS and DrRacket (and my 
> program) runs fine, however when I try to run "raco" I get a message 
> windows with the "Can't find C:\Program FIles\Racket\.\racket Variant:Replace This>.exe":
> 
> 
> 
> I have no extra packages installed or migrated to this installation.
> 
> Alex.
> 
> On Friday, July 26, 2019 at 8:41:15 PM UTC+8, Matthew Flatt wrote:
> >
> > At Tue, 23 Jul 2019 18:50:57 -0600, Matthew Flatt wrote: 
> > > At Tue, 23 Jul 2019 17:47:35 -0700 (PDT), Alex Harsanyi wrote: 
> > > > I installed the windows version of the Racket CS build and, when 
> > trying to 
> > > > run DrRacket I get the following error in a console: 
> > > > 
> > > > variable force-unfasl is not bound 
> > > 
> > > This is a build problem that we're investigating. 
> >
> > The latest pre-release build of Racket CS for Windows installs and runs 
> > (at least for me): 
> >
> >  http://pre-release.racket-lang.org/ 
> >
> >
> > Thanks again for helping us check the pre-release builds! 
> >
> >
> 
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[racket-users] [standard-fish] map of the world

[Alex Harsanyi]

Here is a map of the world, rendered using a 40 line Racket program and 
country outline data from https://geojson-maps.ash.ms/.  You can find the 
source here: 
https://gist.github.com/alex-hhh/2c0f5a02d9e795cbedf90cf84ef84281

[image: world.png]
The program is similar to the one described here, which contains more 
details about the map rendering: 
https://alex-hhh.github.io/2019/05/timezone-visualization.html

Alex.

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[racket-users] [standard-fish] Reverse engineered quilt design

[Daniel Prager]

Here's a photo of the original quilt from Red Pepper Quilts (not my work):



More images, including details, here:
http://bastings54.rssing.com/browser.php?indx=6115008&item=60

And here's my reverse-engineered Racket version:

[image: super-duper-HST-and-QST-quilt.png]

Top-level code, below.


#lang racket

(require threading
 "quilt.rkt")

;; EXAMPLES
;;

;; Build a super-duper quilt from rectangles, hsts, squares, and a
;; few qsts

(define qst_ (qst 1 'black 'white))
(define qst__ (qst 1 'black 'black 'black 'white))
(define hst_ (hst 1 'black 'white 'forward))

(define (around-the-world . ss)
  ; error on (< (length ss) 3)
  (define ts (map (λ (s)
(if (symbol? s)
(square 1 s)
s))
  ss))

(let around ([n(- (* 2 (length ss)) 3)])
  (define half (/ (- n 1) 2))
  (if (= n 3)
  (apply surround (take ts 3))
  (let* ([ps (take (drop ts half) (min (+ half 1)
   (- (length ts) half)))]
 [center (first ps)]
 [corner (last ps)]
 [ts (rest (reverse (rest ps)))]
 [side (apply beside
  (append (make-list (- half (length ts) 1)
 corner)
  ts))])
(surround (around (- n 2))
  (reflect side center)
  corner)

(define (diamond center [surround 'white])
  (4-square (hst 1 surround center 'forward) R))

(define hst-strip
  (~> (reflect (beside/n 4 hst_) qst__)
  (B (H hst_))
  reflect))

(define b1 (around-the-world 'black
 qst_
 'cerise
 'lupine
 'caribbean
 hst_))

(define b2 (around-the-world 'black
 qst_
 'amber
 'cactus
 'maize
 hst_))

(define diamond-strip
  (beside/n 11 (diamond 'black) (diamond 'caribbean)))

(define geese
  (beside/n 9 (A (V hst_) hst_)))

(define quilt
  (~> (grid [b1 (R geese) b2]
[geese (diamond 'maize 'cactus) (H geese)]
[b2 (L geese) b1])
  (surround hst-strip hst_)
  (surround diamond-strip (diamond 'caribbean))
  (add-strips 'cactus)
  (add-strips 'caribbean)
  (add-strips 'black)))


(parameterize ([units 20]
   [show-outline #t])
  (draw quilt))

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[racket-users] Long-term substitute teaching post available at private school

[Jordan Johnson]

Dear Racket friends & teachers,

I’m taking a semester of leave from my teaching position at Kirby School in 
Santa Cruz, CA, and the school is looking for a part-time sub to cover my 
programming class, which I teach based on HtDP. This would be one period, 
Mondays/Wednesdays/Fridays — usually 50 min on M, 85 min on W/F. Small class 
size — I don’t know the exact number, but it’s fewer than 14 students. The 
semester starts mid-August and ends mid-December.

It’s a private school, so this doesn’t require a teaching credential if you 
know the subject well and can teach it.

If you are close enough to Santa Cruz and would want to teach part-time, please 
email me directly and I will put you in touch with the head of school. I won’t 
be checking this mailing list consistently, so please respond in a new email 
thread.

Cheers,
Jordan

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[racket-users] [standard-fish] Lightsabers!

[Justin Zamora]

[Apologies if this gets sent twice. I accidentally sent the first one
to the googlegroups email address]

Stephen De Gabrielle announced this a few days ago on racket-dev, so I
spent my weekend embracing my inner Star Wars nerd and made
lightsabers in Racket. I had never used the pict library before, so it
was also an interesting learning experience.

I created a lightsaber function that produces a pict of a lightsaber.
The only required argument is a color, which can be either a color
name or a color% object. A length can be provided as an optional
argument, as well as a style for the lightsaber hilt. The default hilt
is Luke Skywalker's (#:style 'luke), but you can also select Darth
Vader's (#:style 'vader), Kylo Ren's (#:style 'kylo), or Darth Maul's
(#:style 'maul). See the attached picture for examples of each.

The code is available at https://github.com/zamora/lightsaber

Thanks to Stephen De Gabrielle for providing the incentive to learn
about pict and have some fun!

Justin

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[racket-users] [standard-fish] Lightsabers!

[Justin Zamora]

Stephen De Gabrielle announced this a few days ago on racket-dev, so I
spent my weekend embracing my inner Star Wars nerd and made
lightsabers in Racket. I had never used the pict library before, so it
was also an interesting learning experience.

I created a lightsaber function that produces a pict of a lightsaber.
The only required argument is a color, which can be either a color
name or a color% object. A length can be provided as an optional
argument, as well as a style for the lightsaber hilt. The default hilt
is Luke Skywalker's (#:style 'luke), but you can also select Darth
Vader's (#:style 'vader), Kylo Ren's (#:style 'kylo), or Darth Maul's
(#:style 'maul). See the attached picture for examples of each.

The code is available at https://github.com/zamora/lightsaber

Thanks to Stephen De Gabrielle for providing the incentive to learn
about pict and have some fun!

Justin

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Re: [racket-users] Calling function with Scribble text as argument(s)

[Ben Greenman]

> Now for the next problem.  If I @include-section, an occurrence of
> redtext in the included section is recognised as an unbound identifier.
> Evidently I need to say something to get included sections to inherit
> bindings fro the main file.

`include-section` is much closer to Racket's `require` than TeX's `include`

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[racket-users] [standard-fish] Summer competiton 2019

[Stephen De Gabrielle]

*Subject: [standard-fish] Summer competiton 2019*
*'Summer standard fish competition 2019'*
[image: image]
Competition: Make an image with Racket this summer! Win stickers!

Rules:
* you can make images any way you like. I suggest *pict *or *htdp2e/image,
but you can use whatever you like!*
* Images can be of anything.  Images do not have to be of fish. There is no
advantage in fish images.
* You can enter as many times as you like.

It is easy to enter - just post your entry on racket-users, either by email
or via google groups, with the prefix '[standard-fish]' just like this
email.

Please remember to put [standard-fish] at the begining of the email subject
line so I can easily identfy your entry.

You can paste your code onto the the end of your message, or inlcude a link
to a GitLab or GitHub repository/file,  a GitHub Gist, or anything else
appropriate.
- I don't recommend using attachments on the mailing list/google groups.

What will you win? I'll send Racket stickers
 to the top 10 winners!

Closing date: 1 September 2019 judging will take place in the first two
weeks of September, and winners will be announced 14 September. (I'm away
for most of August so I look forward to seeing your creations on my return)

Note: Not an official Racket competition. I am not a member of the Racket
team, nor am I doing this on their behalf. I am covering the cost of the
stickers and postage.

Any questions: email me at spdegabrielle at gmail dot com

Have a good summer holidays!

Stephen

---

Need help getting started?

   - Quick: An Introduction to Racket with Pictures
   
   - Pict: Functional Pictures
   
   -  2htdp/image 
   - https://github.com/standard-fish/paper-doll - provided by Matthew
   Flatt: *'In case it's of interest, enclosed is some code extracted from
   one of my talks. Start by running "demo.rkt". Someone might be interested
   to play with it or turn it into something better. Since there is no
   documentation, that someone would have to read the code to extract the
   various acceptable values for arguments. The most obvious direction for
   improvement is that choices like hair style and color should have been
   separated into different arguments."*

Having trouble? - ask a question on racket-users. You can also try
stack-overflow and reddit but YMMV.

 standard-fish

[image: image]

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Re: [racket-users] Calling function with Scribble text as argument(s)

[Hendrik Boom]

On Tue, Jul 30, 2019 at 08:08:39PM +0200, Jens Axel Søgaard wrote:
> Den tir. 30. jul. 2019 kl. 19.02 skrev Hendrik Boom  >:
> 
> > I've found this as an example for getting coloured text:
> >
> > #lang scribble/base
> >
> > @(require scribble/core)
> >
> > @(define (colorize #:color c . content)
> > (elem #:style (style #f (list (color-property c)))
> >   content))
> >
> > @colorize[#:color "red"]{WARNING}
> >
> >
> > But what if you want to call colorize from Racket code.
> > For example, to make a function has the colour red built in,
> > I tried
> >
> > @(define (redtext text) (colorize #:color "red" text))
> >
> > which did not work.
> >
> 
> You are right that the contents isn't a single string, so change it to:
> 
> @(define (redtext . contents)
>(colorize #:color "red" contents))
> 
> @redtext{foo}

This works.

It works if the call to redtext is in the same file as the definition.

Now for the next problem.  If I @include-section, an occurrence of 
redtext in the included section is recognised as an unbound identifier.
Evidently I need to say something to get included sections to inherit 
bindings fro the main file.

-- hendrik

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Re: [racket-users] Re: Racket2 possibilities

[George Neuner]

On 7/30/2019 12:59 PM, Atlas Atlas wrote:
вторник, 30 июля 2019 г., 4:40:40 UTC+3 пользователь Sam 
Tobin-Hochstadt написал:



I'm not exactly sure what you're asking for here -- the CL type
system
works very differently -- but local annotation is certainly possible
in Typed Racket. The `ann` form allows you to annotate any expression
at all, ie `(ann 17 Integer)`.

Sam


The idea is you don't need to write this annotations. You can if you want.
In typed racket it is demand.
This became problem with untyped libraries, especially when they 
produce complex data. Or have complex macros.

Sometimes this catches you with iterations.

Simple example
(define (test-f a)
  (string-append a " okay"))
Typed-racket produces error: /"Type Checker: type mismatch expected: 
String given: Any"/ when type of _a_ can easily be inferred.

Solution is to infer type, or leave code untyped in some default way.

Another problem
require/typed - wraps code with contracts what have negative impact on 
performance, sometimes really bad one.

I just find current typed\racket condition unpractical.
I need for example to write my own untyped lib for using another 
untyped lib to simplify interfaces and make impact on performance more 
acceptable.


It seams what I am asking for here is unsound typing.


Latent typing ... what #lang Racket, Scheme and Lisp, etc. provide ... 
is not "unsound":  the data types are known and enforced, but the 
enforcement is at run time, and the result is that there are code size 
(type tests), data size (type tags or other metadata), and performance 
hits due to them.  The whole point of type declarations, type 
inferencing and so forth is to have the types known at compile time for 
sooner error diagnostics, and to increase performance by eliminating 
unneeded runtime testing.




Another option is to force! typed racket on all levels in all libs.

I am not so big expert in theory of language design..
There is some paper I found 
www.ccis.northeastern.edu/home/types/publications/gradual-dead/pre-treatment.pdf 
 
on this matter, called "Is Sound Gradual Typing Dead?" from 
Northeastern University, it highlights some of the problems in more 
scientific way.




George

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Re: [racket-users] Re: Racket2 possibilities

[George Neuner]

Hi Sam,

On 7/29/2019 9:40 PM, Sam Tobin-Hochstadt wrote:

On Mon, Jul 29, 2019 at 9:31 PM George Neuner  wrote:

> To me, TypedRacket feels much more like ML than like Dylan or Common
> Lisp.  Type inference is great - when it works. Coarse grained scope
> encompassing declarations are great - when you can figure out what
> they should be.  Reducing busywork and the cognative load on the
> programmer seems like it always should be a Good Thing.  But when
> inference fails and the declarations are unfathomable, and there is no
> easy way around the problem save by falling back to SLOW untyped code,
> then typing becomes a PITA.  To my thinking, there needs to be some
> middle ground - like CL's 'the' operator or Dylan's local annotations
> - that can disambiguate problems on the spot.

I'm not exactly sure what you're asking for here -- the CL type system
works very differently -- but local annotation is certainly possible
in Typed Racket. The `ann` form allows you to annotate any expression
at all, ie `(ann 17 Integer)`.


'ann'  operand order puts the (possibly lengthy) code expression before 
the (typically much shorter) type declaration.  This is the reverse of 
the way Lisp does it, and, IMO, it makes 'ann' expressions harder to read.



I think Atlas nailed the crux of my issue: that Dylan and CL permit you 
to add manifest typing incrementally as you desire or see need, whereas 
TypedRacket requires at least some typing (of variables) right from the 
very beginning and then it continues to natter at you about things you 
don't necessarily care about  in the moment.


What I want is to be able to freely mix latent typed and manifest typed 
code, and not worry about crossing boundaries until performance 
considerations require that I do so.   That said, even though Common 
Lisp is closer to what I want - I don't use it precisely because it is 
Lisp ... I much prefer Scheme.


YMMV,
George

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Re: [racket-users] Calling function with Scribble text as argument(s)

[Jens Axel Søgaard]

Den tir. 30. jul. 2019 kl. 19.02 skrev Hendrik Boom :

> I've found this as an example for getting coloured text:
>
> #lang scribble/base
>
> @(require scribble/core)
>
> @(define (colorize #:color c . content)
> (elem #:style (style #f (list (color-property c)))
>   content))
>
> @colorize[#:color "red"]{WARNING}
>
>
> But what if you want to call colorize from Racket code.
> For example, to make a function has the colour red built in,
> I tried
>
> @(define (redtext text) (colorize #:color "red" text))
>
> which did not work.
>

You are right that the contents isn't a single string, so change it to:

@(define (redtext . contents)
   (colorize #:color "red" contents))

@redtext{foo}

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[racket-users] Re: Calling function with Scribble text as argument(s)

['Joel Dueck' via Racket Users]

On Tuesday, July 30, 2019 at 12:02:02 PM UTC-5, Hendrik Boom wrote:
>
> For example, to make a function has the colour red built in, 
> I tried 
>
> @(define (redtext text) (colorize #:color "red" text)) 
>
> which did not work. 
>

When you say "which did not work" — what didn't work exactly? If I 
concatenate this `@define` with your top example and add

@redtext{WARNING AGAIN}

…I get the expected output in DrRacket, no errors.

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[racket-users] Calling function with Scribble text as argument(s)

[Hendrik Boom]

I've found this as an example for getting coloured text:

#lang scribble/base

@(require scribble/core)

@(define (colorize #:color c . content)
(elem #:style (style #f (list (color-property c)))
  content))

@colorize[#:color "red"]{WARNING}


But what if you want to call colorize from Racket code.
For example, to make a function has the colour red built in,
I tried

@(define (redtext text) (colorize #:color "red" text))

which did not work.

Presumably the (summary text) has to accept text as a bunch of 
arguments, not just one.
 and the last argument to colorize needs to be 
understood accordingly.

By analogy to the definition of colorize I probably have to start with
somethng like
@(define (summary . text)  
but then how to pass text to colorize as a bunch of arguments, not 
just one?


-- hendrik


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Re: [racket-users] Re: Racket2 possibilities

[Atlas Atlas]

вторник, 30 июля 2019 г., 4:40:40 UTC+3 пользователь Sam Tobin-Hochstadt 
написал:

>
> I'm not exactly sure what you're asking for here -- the CL type system 
> works very differently -- but local annotation is certainly possible 
> in Typed Racket. The `ann` form allows you to annotate any expression 
> at all, ie `(ann 17 Integer)`. 
>
> Sam 
>

The idea is you don't need to write this annotations. You can if you want.
In typed racket it is demand.
This became problem with untyped libraries, especially when they produce 
complex data. Or have complex macros.
Sometimes this catches you with iterations.

Simple example 
(define (test-f a)
  (string-append a " okay"))
Typed-racket produces error: *"Type Checker: type mismatch expected: String 
given: Any"* when type of *a* can easily be inferred.
Solution is to infer type, or leave code untyped in some default way.

Another problem
require/typed - wraps code with contracts what have negative impact on 
performance, sometimes really bad one.
I just find current typed\racket condition unpractical.
I need for example to write my own untyped lib for using another untyped 
lib to simplify interfaces and make impact on performance more acceptable.

It seams what I am asking for here is unsound typing.

Another option is to force! typed racket on all levels in all libs.

I am not so big expert in theory of language design..
There is some paper I found 
www.ccis.northeastern.edu/home/types/publications/gradual-dead/pre-treatment.pdf
 
on this matter, called "Is Sound Gradual Typing Dead?" from Northeastern 
University, it highlights some of the problems in more scientific way.

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