Re: [racket-users] [PSA] Upcoming projects

[Daniel Prager]

Hi Eric

They all sound great.

I'm particularly interested in the first two, and was very impressed by the
Diagram project gallery
,
and it would be great to see in Racket.

Quick question: Why *Algebraic* Racket?

Dan

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Re: [racket-users] Pattern matching as computation

[David Storrs]

Oh, neat.  Thank you, Sorawee.

On Thu, Jun 27, 2019 at 7:26 PM Sorawee Porncharoenwase <
sorawee.pw...@gmail.com> wrote:

> If you want only one match, it seems what you really want is ~seq-like
> form from syntax/parse. E.g.,
>
> #lang racket
>
> (require syntax/parse)
>
> (define ->value syntax->datum)
>
> (define (apply-lift op args)
>   (datum->syntax #f (apply op (->value args
>
> (syntax-parse (vector 1 2 3 4)
>   [#(a {~and {~seq {~between b 2 2} ...}
>  {~bind [x (apply-lift + #'(b ...))]}} c)
>(->value #'(a (b ...) c x))])
> ;; => '(1 (2 3) 4 5)
>
> (struct person (name age) #:prefab)
> (struct horse (color owner) #:prefab)
>
> (syntax-parse (vector 'brown 'bob 23)
>   [#(the-color {~and {~seq args ...}
>  {~bind [the-owner (apply-lift person #'(args ...))]}})
>(->value (apply-lift horse #'(the-color the-owner)))])
> ;; => '#s(horse brown #s(person bob 23))
>
>
>
>
>
> On Thu, Jun 27, 2019 at 3:31 PM David Storrs 
> wrote:
>
>>
>>
>> On Thu, Jun 27, 2019 at 5:13 PM Eric Griffis  wrote:
>>
>>> On Thu, Jun 27, 2019 at 11:56 AM David Storrs 
>>> wrote:
>>> >
>>> > Suppose instead I wanted to have a pattern like so (this does not
>>> work):
>>> >
>>> > (match (vector 1 2 3 4)
>>> >   [(vector a (app + b ..2 x) c) (list a b c x)]
>>> > ; => '(1 (2 3) 4 5))  ;  NB:  does not work
>>>
>>> We have a few problems here.
>>>
>>> The pattern (vector a ? c) does not match the shape of the val-expr
>>> (vector 1 2 3 4).
>>>
>>> In the second sub-pattern (app + b ..2 x), Racket complains `..2' is an
>>> "incorrect use of ... in pattern" because every sub-pattern of `app' must
>>> independently match the result of (+ 2).
>>>
>>> To get the expected result '(1 (2 3) 4 5) from the actual result (list
>>> a b
>>> c x), we'd need the following bindings:
>>>
>>> a --> 1
>>> b --> '(2 3)
>>> c --> 4
>>> x --> 5
>>>
>>> At this point, I'm not sure what you're trying to do. Maybe you're trying
>>> to bind `b' to '(2 3), then `x' with the sum (+ 2 3), then `c' with 4.
>>>
>>> Here's one way to do it from within a single pattern:
>>>
>>> (match (vector 1 2 3 4)
>>>   [(and (vector a _ _ c)
>>> (app (λ (vec)
>>>(match vec
>>>  [(vector _ p q _)
>>>   (list (list p q) (+ p q))]))
>>>  (list b x)))
>>>(list a b c x)])
>>>
>>> > Less trivially, I'd like to be able to do something like this:
>>> >
>>> > #lang racket
>>> > (struct person (name age) #:prefab)
>>> > (struct horse (color owner) #:prefab)
>>> >
>>> > ; The following does not work
>>> > (match (vector 'brown 'bob 23)
>>> >   [(vector the-color (app (curry apply person) args ... the-owner))
>>> >(horse the-color the-owner)])
>>>
>>> Here's an adaptation of the above technique that works:
>>>
>>> (match (vector 'brown 'bob 23)
>>>   [(and (vector the-color _ _)
>>> (app (λ (vec)
>>>(match vec
>>>  [(vector _ name age)
>>>   (person name age)]))
>>>  the-owner))
>>>(horse the-color the-owner)])
>>>
>>
>> Makes sense -- it's two matches,  but still within one sexp.  Thanks.
>>
>>
>>> Incidentally, Algebraic Racket is designed for this:
>>>
>>> #lang algebraic/racket/base
>>>
>>> (require (prefix-in algebraic- algebraic/racket/base/forms))
>>>
>>> (algebraic-case (vector 1 2 3 4)
>>>   [#(a p q c)
>>>#:with b (list p q)
>>>#:with x (+ p q)
>>>(list a b c x)])
>>>
>>> (algebraic-case (vector 'brown 'bob 23)
>>>   [#(the-color name age)
>>>#:with the-owner (person name age)
>>>(horse the-color the-owner)])
>>>
>>> If a #:with directive fails, the overall match fails:
>>>
>>> (algebraic-case (vector 'brown 'bob 23)
>>>   [#(the-color name age)
>>>#:with the-owner #f
>>>#:with (person _ _) the-owner
>>>(horse the-color the-owner)])
>>>
>>>
>> That is drop-dead sexy.  Thanks, Eric.
>>
>>
>> Eric
>>>
>>> --
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>> 
>> .
>> For more options, visit https://groups.google.com/d/optout.
>>
>

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[racket-users] [PSA] Upcoming projects

[Eric Griffis]

Hello everyone,

Over the next few months, I will be breaking ground on three new projects.

== A diagramming library ==

  An Algebraic Racket port of Haskell's diagrams library:

  https://archives.haskell.org/projects.haskell.org/diagrams/

  I love this design. It's like Pict, but the API is structured as a
  monoid under cc-superimpose.

== A dynamic, interactive data visualization library ==

  An aggressive Algebraic Racket adaptation of the parts of D3.js I like.

  Initial use cases:
  - concurrent / distributed process network visualizations
  - hybrid text/graphical UIs with automatic layout
  - a generic feed browser

== A digital audio workstation library ==

  An experiment in real-time interactive Neuron programming.

  The base package will include a basic synth, a sampler, a sequencer, and
  a multi-track recorder -- like a developer API for Fruity Loops.

  Endpoints for MIDI and audio I/O should be easy to build with packages
  in the official repo.

  Optimistic feature list:
  - multi-track recording and playback (audio & MIDI)
  - non-destructive edits
  - mix automation
  - inter-process signal routing
  - global clock synchronization

I will then combine these projects into a hybrid DAW / VJ instrument and
target a live A/V performance for FARM 2020, the SIGPLAN workshop for
functional art and music co-located with ICFP.

If any part of this interests you, however large or small, reach out!

If you are working on related software, or planning to, speak up!

Eric

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Re: [racket-users] Pattern matching as computation

[Sorawee Porncharoenwase]

If you want only one match, it seems what you really want is ~seq-like form
from syntax/parse. E.g.,

#lang racket

(require syntax/parse)

(define ->value syntax->datum)

(define (apply-lift op args)
  (datum->syntax #f (apply op (->value args

(syntax-parse (vector 1 2 3 4)
  [#(a {~and {~seq {~between b 2 2} ...}
 {~bind [x (apply-lift + #'(b ...))]}} c)
   (->value #'(a (b ...) c x))])
;; => '(1 (2 3) 4 5)

(struct person (name age) #:prefab)
(struct horse (color owner) #:prefab)

(syntax-parse (vector 'brown 'bob 23)
  [#(the-color {~and {~seq args ...}
 {~bind [the-owner (apply-lift person #'(args ...))]}})
   (->value (apply-lift horse #'(the-color the-owner)))])
;; => '#s(horse brown #s(person bob 23))





On Thu, Jun 27, 2019 at 3:31 PM David Storrs  wrote:

>
>
> On Thu, Jun 27, 2019 at 5:13 PM Eric Griffis  wrote:
>
>> On Thu, Jun 27, 2019 at 11:56 AM David Storrs 
>> wrote:
>> >
>> > Suppose instead I wanted to have a pattern like so (this does not work):
>> >
>> > (match (vector 1 2 3 4)
>> >   [(vector a (app + b ..2 x) c) (list a b c x)]
>> > ; => '(1 (2 3) 4 5))  ;  NB:  does not work
>>
>> We have a few problems here.
>>
>> The pattern (vector a ? c) does not match the shape of the val-expr
>> (vector 1 2 3 4).
>>
>> In the second sub-pattern (app + b ..2 x), Racket complains `..2' is an
>> "incorrect use of ... in pattern" because every sub-pattern of `app' must
>> independently match the result of (+ 2).
>>
>> To get the expected result '(1 (2 3) 4 5) from the actual result (list a
>> b
>> c x), we'd need the following bindings:
>>
>> a --> 1
>> b --> '(2 3)
>> c --> 4
>> x --> 5
>>
>> At this point, I'm not sure what you're trying to do. Maybe you're trying
>> to bind `b' to '(2 3), then `x' with the sum (+ 2 3), then `c' with 4.
>>
>> Here's one way to do it from within a single pattern:
>>
>> (match (vector 1 2 3 4)
>>   [(and (vector a _ _ c)
>> (app (λ (vec)
>>(match vec
>>  [(vector _ p q _)
>>   (list (list p q) (+ p q))]))
>>  (list b x)))
>>(list a b c x)])
>>
>> > Less trivially, I'd like to be able to do something like this:
>> >
>> > #lang racket
>> > (struct person (name age) #:prefab)
>> > (struct horse (color owner) #:prefab)
>> >
>> > ; The following does not work
>> > (match (vector 'brown 'bob 23)
>> >   [(vector the-color (app (curry apply person) args ... the-owner))
>> >(horse the-color the-owner)])
>>
>> Here's an adaptation of the above technique that works:
>>
>> (match (vector 'brown 'bob 23)
>>   [(and (vector the-color _ _)
>> (app (λ (vec)
>>(match vec
>>  [(vector _ name age)
>>   (person name age)]))
>>  the-owner))
>>(horse the-color the-owner)])
>>
>
> Makes sense -- it's two matches,  but still within one sexp.  Thanks.
>
>
>> Incidentally, Algebraic Racket is designed for this:
>>
>> #lang algebraic/racket/base
>>
>> (require (prefix-in algebraic- algebraic/racket/base/forms))
>>
>> (algebraic-case (vector 1 2 3 4)
>>   [#(a p q c)
>>#:with b (list p q)
>>#:with x (+ p q)
>>(list a b c x)])
>>
>> (algebraic-case (vector 'brown 'bob 23)
>>   [#(the-color name age)
>>#:with the-owner (person name age)
>>(horse the-color the-owner)])
>>
>> If a #:with directive fails, the overall match fails:
>>
>> (algebraic-case (vector 'brown 'bob 23)
>>   [#(the-color name age)
>>#:with the-owner #f
>>#:with (person _ _) the-owner
>>(horse the-color the-owner)])
>>
>>
> That is drop-dead sexy.  Thanks, Eric.
>
>
> Eric
>>
>> --
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Re: [racket-users] Pattern matching as computation

[David Storrs]

On Thu, Jun 27, 2019 at 5:13 PM Eric Griffis  wrote:

> On Thu, Jun 27, 2019 at 11:56 AM David Storrs 
> wrote:
> >
> > Suppose instead I wanted to have a pattern like so (this does not work):
> >
> > (match (vector 1 2 3 4)
> >   [(vector a (app + b ..2 x) c) (list a b c x)]
> > ; => '(1 (2 3) 4 5))  ;  NB:  does not work
>
> We have a few problems here.
>
> The pattern (vector a ? c) does not match the shape of the val-expr
> (vector 1 2 3 4).
>
> In the second sub-pattern (app + b ..2 x), Racket complains `..2' is an
> "incorrect use of ... in pattern" because every sub-pattern of `app' must
> independently match the result of (+ 2).
>
> To get the expected result '(1 (2 3) 4 5) from the actual result (list a b
> c x), we'd need the following bindings:
>
> a --> 1
> b --> '(2 3)
> c --> 4
> x --> 5
>
> At this point, I'm not sure what you're trying to do. Maybe you're trying
> to bind `b' to '(2 3), then `x' with the sum (+ 2 3), then `c' with 4.
>
> Here's one way to do it from within a single pattern:
>
> (match (vector 1 2 3 4)
>   [(and (vector a _ _ c)
> (app (λ (vec)
>(match vec
>  [(vector _ p q _)
>   (list (list p q) (+ p q))]))
>  (list b x)))
>(list a b c x)])
>
> > Less trivially, I'd like to be able to do something like this:
> >
> > #lang racket
> > (struct person (name age) #:prefab)
> > (struct horse (color owner) #:prefab)
> >
> > ; The following does not work
> > (match (vector 'brown 'bob 23)
> >   [(vector the-color (app (curry apply person) args ... the-owner))
> >(horse the-color the-owner)])
>
> Here's an adaptation of the above technique that works:
>
> (match (vector 'brown 'bob 23)
>   [(and (vector the-color _ _)
> (app (λ (vec)
>(match vec
>  [(vector _ name age)
>   (person name age)]))
>  the-owner))
>(horse the-color the-owner)])
>

Makes sense -- it's two matches,  but still within one sexp.  Thanks.


> Incidentally, Algebraic Racket is designed for this:
>
> #lang algebraic/racket/base
>
> (require (prefix-in algebraic- algebraic/racket/base/forms))
>
> (algebraic-case (vector 1 2 3 4)
>   [#(a p q c)
>#:with b (list p q)
>#:with x (+ p q)
>(list a b c x)])
>
> (algebraic-case (vector 'brown 'bob 23)
>   [#(the-color name age)
>#:with the-owner (person name age)
>(horse the-color the-owner)])
>
> If a #:with directive fails, the overall match fails:
>
> (algebraic-case (vector 'brown 'bob 23)
>   [#(the-color name age)
>#:with the-owner #f
>#:with (person _ _) the-owner
>(horse the-color the-owner)])
>
>
That is drop-dead sexy.  Thanks, Eric.


Eric
>
>

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Re: [racket-users] Pattern matching as computation

[Eric Griffis]

On Thu, Jun 27, 2019 at 11:56 AM David Storrs 
wrote:
>
> Suppose instead I wanted to have a pattern like so (this does not work):
>
> (match (vector 1 2 3 4)
>   [(vector a (app + b ..2 x) c) (list a b c x)]
> ; => '(1 (2 3) 4 5))  ;  NB:  does not work

We have a few problems here.

The pattern (vector a ? c) does not match the shape of the val-expr
(vector 1 2 3 4).

In the second sub-pattern (app + b ..2 x), Racket complains `..2' is an
"incorrect use of ... in pattern" because every sub-pattern of `app' must
independently match the result of (+ 2).

To get the expected result '(1 (2 3) 4 5) from the actual result (list a b
c x), we'd need the following bindings:

a --> 1
b --> '(2 3)
c --> 4
x --> 5

At this point, I'm not sure what you're trying to do. Maybe you're trying
to bind `b' to '(2 3), then `x' with the sum (+ 2 3), then `c' with 4.

Here's one way to do it from within a single pattern:

(match (vector 1 2 3 4)
  [(and (vector a _ _ c)
(app (λ (vec)
   (match vec
 [(vector _ p q _)
  (list (list p q) (+ p q))]))
 (list b x)))
   (list a b c x)])

> Less trivially, I'd like to be able to do something like this:
>
> #lang racket
> (struct person (name age) #:prefab)
> (struct horse (color owner) #:prefab)
>
> ; The following does not work
> (match (vector 'brown 'bob 23)
>   [(vector the-color (app (curry apply person) args ... the-owner))
>(horse the-color the-owner)])

Here's an adaptation of the above technique that works:

(match (vector 'brown 'bob 23)
  [(and (vector the-color _ _)
(app (λ (vec)
   (match vec
 [(vector _ name age)
  (person name age)]))
 the-owner))
   (horse the-color the-owner)])

Incidentally, Algebraic Racket is designed for this:

#lang algebraic/racket/base

(require (prefix-in algebraic- algebraic/racket/base/forms))

(algebraic-case (vector 1 2 3 4)
  [#(a p q c)
   #:with b (list p q)
   #:with x (+ p q)
   (list a b c x)])

(algebraic-case (vector 'brown 'bob 23)
  [#(the-color name age)
   #:with the-owner (person name age)
   (horse the-color the-owner)])

If a #:with directive fails, the overall match fails:

(algebraic-case (vector 'brown 'bob 23)
  [#(the-color name age)
   #:with the-owner #f
   #:with (person _ _) the-owner
   (horse the-color the-owner)])

Eric

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[racket-users] Pattern matching as computation

[David Storrs]

This works:

(match (vector 1 2 3 4)
 [(vector a b (app add1 c) d)
  (list a b c d)])
; => '(1 2 4 4)

Suppose instead I wanted to have a pattern like so (this does not work):

(match (vector 1 2 3 4)
  [(vector a (app + b ..2 x) c) (list a b c x)]
; => '(1 (2 3) 4 5))  ;  NB:  does not work

Is there a way to do this?


Less trivially, I'd like to be able to do something like this:

#lang racket
(struct person (name age) #:prefab)
(struct horse (color owner) #:prefab)

; The following does not work
(match (vector 'brown 'bob 23)
  [(vector the-color (app (curry apply person) args ... the-owner))
   (horse the-color the-owner)])

I've been through the pattern matching docs in some detail and tried
various things, but my brain-fu is weak.

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RE: [racket-users] problem with current-error-port in scribbleinteraction

[Jos Koot]

Perfect. (with-handlers ((exn:fail? exception-handler)) ...) works nice.
Thanks very much for your rapid response,
Jos

From: Ryan Culpepper
Sent: 27 June 2019 13:36
To: Jos Koot; Racket Users
Subject: Re: [racket-users] problem with current-error-port in 
scribbleinteraction

The `uncaught-exception-handler` parameter controls the *bottom* of the 
exception handler stack, so it won't override the exception handler 
installed by Scribble's `interaction` form. If you use `with-handlers` 
(or `call-with-exception-handler`) instead, it should work.

The `uncaught-exception-handler` value is inherited by new threads, so 
it shouldn't refer to a specific escape continuation. That continuation 
(maybe the whole parent thread) may be gone by the time a child thread 
raises an exception.

Ryan


On 6/27/19 12:42 PM, Jos Koot wrote:
>
>
> Hi,
>
> The attachments are assumed to reside in the same directory and
> are reduced forms of more elaborated code.
> In module try-rkt I have code that captures errors such as
> to avoid an error-message being written on the current-error-port,
> to retrieve the error-message and to return normally.
> This works well as shown in module test-try-rkt.
> However, in a scribble interaction as shown in module try-scrbl,
> I get page try.html in which the interaction shows the error message
> and does not show the value returned by the test-proc.
>
> How can I make the interaction behave like in module test-try.rkt?
>
> In module try.rkt the use of eval is necessary.
>
> It is a strongly reduced version of a testing system
>
> that accepts sexprs and checks the returned values, the standard output and
>
> the error-message when an error is expected.
>
> Best wishes, Jos

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Re: [racket-users] problem with current-error-port in scribble interaction

[Ryan Culpepper]

The `uncaught-exception-handler` parameter controls the *bottom* of the 
exception handler stack, so it won't override the exception handler 
installed by Scribble's `interaction` form. If you use `with-handlers` 
(or `call-with-exception-handler`) instead, it should work.


The `uncaught-exception-handler` value is inherited by new threads, so 
it shouldn't refer to a specific escape continuation. That continuation 
(maybe the whole parent thread) may be gone by the time a child thread 
raises an exception.


Ryan


On 6/27/19 12:42 PM, Jos Koot wrote:



Hi,



The attachments are assumed to reside in the same directory and

are reduced forms of more elaborated code.

In module try-rkt I have code that captures errors such as

to avoid an error-message being written on the current-error-port,

to retrieve the error-message and to return normally.

This works well as shown in module test-try-rkt.

However, in a scribble interaction as shown in module try-scrbl,

I get page try.html in which the interaction shows the error message

and does not show the value returned by the test-proc.



How can I make the interaction behave like in module test-try.rkt?



In module try.rkt the use of eval is necessary.

It is a strongly reduced version of a testing system

that accepts sexprs and checks the returned values, the standard output and

the error-message when an error is expected.



Best wishes, Jos

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[racket-users] problem with current-error-port in scribble interaction

[Jos Koot]

Hi,

The attachments are assumed to reside in the same directory and
are reduced forms of more elaborated code.
In module try-rkt I have code that captures errors such as
to avoid an error-message being written on the current-error-port,
to retrieve the error-message and to return normally.
This works well as shown in module test-try-rkt.
However, in a scribble interaction as shown in module try-scrbl,
I get page try.html in which the interaction shows the error message
and does not show the value returned by the test-proc.

How can I make the interaction behave like in module test-try.rkt?

In module try.rkt the use of eval is necessary.
It is a strongly reduced version of a testing system
that accepts sexprs and checks the returned values, the standard output and
the error-message when an error is expected.

Best wishes, Jos

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test-try.rkt
Description: Binary data
Title: Try-test

•Try-testTry-testtest-procTry-testJacob J. A. Koot (require "try.rkt")procedure(test-proc) → void?blah blah
> (require "try.rkt")> (test-proc)monkey 

try.rkt
Description: Binary data


try.scrbl
Description: Binary data

[racket-users] new or make-object?

[Amir Teymuri]

According to the docs: 

The make-object 
> 
>  
> procedure creates a new object with by-position initialization arguments, 
> the new 
> 
>  
> form creates a new object with by-name initialization arguments
>


Is the way of arguments specification the only difference between new and 
make-object? 

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