Re: [racket-users] Scrolling problem in DrRacket with high pictures in slideshow

[Robby Findler]

Ah, I didn't realize they weren't even there. :)

Probably the right thing is to override the default behavior in a
pict-snip-specific way.

Robby


On Fri, Aug 11, 2017 at 10:53 AM, Laurent  wrote:
> Thanks Robby.
>
> I suppose this is the class in question:
> https://github.com/racket/pict-snip/blob/master/pict-snip-lib/pict/snip.rkt
>
> though there is not mention to "scroll". Could the problem lie in the more
> general snip% then?
>
> On Fri, Aug 11, 2017 at 2:05 PM, Robby Findler 
> wrote:
>>
>> My guess would be that the problem lies with the pict-snip% class and
>> how it implements the methods with the word "scroll" in their name.
>>
>> Robby
>>
>>
>> On Fri, Aug 11, 2017 at 7:58 AM, Laurent  wrote:
>> > Hi all,
>> >
>> > After running the following program in DrRacket on Ubuntu I can't use
>> > the
>> > scrollbar to see the text at the bottom (increase 1000 so that the text
>> > does
>> > not appear on the first page of the interactions).
>> >
>> > #lang racket
>> > (require slideshow)
>> >
>> > (vl-append (rectangle 10 1000)
>> >(t "Can you see me?"))
>> >
>> > Anyone knows a simple way to solve this?
>> >
>> > Thanks!
>> > Laurent
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> > Groups
>> > "Racket Users" group.
>> > To unsubscribe from this group and stop receiving emails from it, send
>> > an
>> > email to racket-users+unsubscr...@googlegroups.com.
>> > For more options, visit https://groups.google.com/d/optout.
>
>

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Re: [racket-users] Scrolling problem in DrRacket with high pictures in slideshow

[Laurent]

Thanks Robby.

I suppose this is the class in question:
https://github.com/racket/pict-snip/blob/master/pict-snip-lib/pict/snip.rkt

though there is not mention to "scroll". Could the problem lie in the more
general snip% then?

On Fri, Aug 11, 2017 at 2:05 PM, Robby Findler 
wrote:

> My guess would be that the problem lies with the pict-snip% class and
> how it implements the methods with the word "scroll" in their name.
>
> Robby
>
>
> On Fri, Aug 11, 2017 at 7:58 AM, Laurent  wrote:
> > Hi all,
> >
> > After running the following program in DrRacket on Ubuntu I can't use the
> > scrollbar to see the text at the bottom (increase 1000 so that the text
> does
> > not appear on the first page of the interactions).
> >
> > #lang racket
> > (require slideshow)
> >
> > (vl-append (rectangle 10 1000)
> >(t "Can you see me?"))
> >
> > Anyone knows a simple way to solve this?
> >
> > Thanks!
> > Laurent
> >
> > --
> > You received this message because you are subscribed to the Google Groups
> > "Racket Users" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
> > email to racket-users+unsubscr...@googlegroups.com.
> > For more options, visit https://groups.google.com/d/optout.
>

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Re: [racket-users] Readtable - allowing pipes (bars) in operator

[Martin Janiczek]

Damn, you're right:

---

martin@janiczek ~ $ cat test.rkt
#lang racket

(parameterize ([read-accept-bar-quote #f])
  (let* ([input "(|| a b)"]
 [result (read (open-input-string input))])
(begin
  (println result)
  (println (first result))
  (println (symbol? (first result))


martin@janiczek ~ $ racket test.rkt
'(|| a b)
'||
#t

martin@janiczek ~ $

---

I don't know what I did wrong before. Thank you!

On Friday, August 11, 2017 at 3:26:20 PM UTC+2, Matthew Flatt wrote:
> Setting `read-accept-bar-quote` to #f should do what you want. Can you
> say more about how you tried to use it --- maybe providing a program
> that doesn't behave the way you expect?
> 
> At Fri, 11 Aug 2017 00:46:17 -0700 (PDT), Martin Janiczek wrote:
> > Hello everybody,
> > 
> > is there a way to tell the `(read)` function not to interpret `|` as an 
> > "copy 
> > this verbatim" delimiter?
> > 
> > What I want to do is:
> > (read "(|| a b)") ;=> '(|| a b)
> > (read "(<| a b)") ;=> '(<| a b)
> > etc. - allow `|` as a symbol.
> > 
> > I know about readtables - dabbled with them before and they seem like the 
> > right tool for the job. But in this case, my last attempt was:
> > 
> > (make-readtable (current-readtable)
> >   #\|
> >   'terminating-macro
> >   read-as-symbol)
> > 
> > and I couldn't get the `read-as-symbol` function right. Also experimented 
> > with 
> > `read-accept-bar-quote` parameter but no dice.
> > 
> > Any help/pointers?

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Re: [racket-users] Readtable - allowing pipes (bars) in operator

[Matthew Flatt]

Setting `read-accept-bar-quote` to #f should do what you want. Can you
say more about how you tried to use it --- maybe providing a program
that doesn't behave the way you expect?

At Fri, 11 Aug 2017 00:46:17 -0700 (PDT), Martin Janiczek wrote:
> Hello everybody,
> 
> is there a way to tell the `(read)` function not to interpret `|` as an "copy 
> this verbatim" delimiter?
> 
> What I want to do is:
> (read "(|| a b)") ;=> '(|| a b)
> (read "(<| a b)") ;=> '(<| a b)
> etc. - allow `|` as a symbol.
> 
> I know about readtables - dabbled with them before and they seem like the 
> right tool for the job. But in this case, my last attempt was:
> 
> (make-readtable (current-readtable)
>   #\|
>   'terminating-macro
>   read-as-symbol)
> 
> and I couldn't get the `read-as-symbol` function right. Also experimented 
> with 
> `read-accept-bar-quote` parameter but no dice.
> 
> Any help/pointers?

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Re: [racket-users] Scrolling problem in DrRacket with high pictures in slideshow

[Robby Findler]

My guess would be that the problem lies with the pict-snip% class and
how it implements the methods with the word "scroll" in their name.

Robby


On Fri, Aug 11, 2017 at 7:58 AM, Laurent  wrote:
> Hi all,
>
> After running the following program in DrRacket on Ubuntu I can't use the
> scrollbar to see the text at the bottom (increase 1000 so that the text does
> not appear on the first page of the interactions).
>
> #lang racket
> (require slideshow)
>
> (vl-append (rectangle 10 1000)
>(t "Can you see me?"))
>
> Anyone knows a simple way to solve this?
>
> Thanks!
> Laurent
>
> --
> You received this message because you are subscribed to the Google Groups
> "Racket Users" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to racket-users+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.

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[racket-users] Scrolling problem in DrRacket with high pictures in slideshow

[Laurent]

Hi all,

After running the following program in DrRacket on Ubuntu I can't use the
scrollbar to see the text at the bottom (increase 1000 so that the text
does not appear on the first page of the interactions).

#lang racket
(require slideshow)

(vl-append (rectangle 10 1000)
   (t "Can you see me?"))

Anyone knows a simple way to solve this?

Thanks!
Laurent

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Re: [racket-users] A bug in the Typed Racket system?

[Sourav Datta]

Thanks for the clarification.

On 09-Aug-2017 3:29 AM, "Sam Tobin-Hochstadt"  wrote:

> The reason that Typed Racket chooses the istantiation `Nothing` here
> is that because `a` is used in both a positive and negative position
> (both as an input and an output) in the type of the `val` field,
> there's no way to pick a "best" choice for `a`. `(Foo Integer)` is not
> a subtype of `(Foo Any)`, for example. Furthermore, whatever Typed
> Racket chooses for `a`, the function application will type check.
> Typed Racket therefore picks the smallest type that works, which is
> `Nothing`.
>
> This actually tells you more about your second program -- in
> particular, you can't ever call the `val` function from the `(Foo a)`,
> because you can't construct a value of type `a`.
>
> Sam
>
> On Fri, Jul 21, 2017 at 1:40 PM, Sourav Datta 
> wrote:
> > On Friday, July 21, 2017 at 9:06:16 PM UTC+5:30, Ben Greenman wrote:
> >> Type inference is failing you again.
> >
> > Yes, well, that seems to be a common theme whenever I hover around the
> these type of areas which are uncommon but works perfectly fine in untyped
> Racket.
> >
> >>
> >>
> >> If you instantiate `foo/s`, you get the type you expect:
> >>
> >>
> >>
> >> #lang typed/racket
> >>
> >>
> >> (struct (a) Foo ([val : (-> a a)]))
> >>
> >>
> >> (: foo/s (All (a b)
> >>   (-> (-> a b)
> >>   (-> (Foo a)
> >>   (Foo b)
> >>   (Foo b)
> >> (define (foo/s f)
> >>   (λ ([f1 : (Foo a)]
> >>   [f2 : (Foo b)])
> >> f2))
> >>
> >>
> >>
> >>
> >> (define r1 (#{foo/s @ Integer String} (λ ([x : Integer]) (format "~a"
> x
> >>
> >> ;> r1
> >> ;- : (-> (Foo Integer) (Foo String) (Foo String))
> >
> > Yes, that works fine. For my personal use it is good enough, but
> exporting that function as a library would require every user to annotate
> the type whenever they want to call it, even for very simple types - which
> is not a very good experience for a typed language.
> >
> >>
> >>
> >>
> >>
> >> I wouldn't call this a bug, but it's definitely a program that a better
> type inferencer should accept.
> >
> > In other cases where type inference fails, the compiler bails out with
> an error (even though that is a confusing one like `expected: (Seq a)
> given: (Seq Integer)`). But here:
> >
> > 1. The inference did not fail but assumed it's Nothing just because I
> changed the function signature from (-> a) to (-> a a). I can't understand
> why the inference fails for this change. And on top of this,
> >
> > 2. The function type is clearly specified as (-> (Foo a) (Foo b) (Foo
> b)) and it can unify a = Integer, b = String, from the first argument
> alone. So, even though a is Integer, it still produces a = Nothing, without
> a compile error. Integer =/= Nothing. Seems very close to a bug in the type
> deduction algorithm.
> >
> >
> >>
> >>
> >> On Fri, Jul 21, 2017 at 5:19 AM, Sourav Datta 
> wrote:
> >> Consider this program,
> >>
> >>
> >>
> >> #lang typed/racket
> >>
> >>
> >>
> >> (struct (a) Foo ([val : (-> a)]))
> >>
> >>
> >>
> >> (: foo/s (All (a b)
> >>
> >>   (-> (-> a b)
> >>
> >>   (-> (Foo a)
> >>
> >>   (Foo b)
> >>
> >>   (Foo b)
> >>
> >> (define (foo/s f)
> >>
> >>   (λ ([f1 : (Foo a)]
> >>
> >>   [f2 : (Foo b)])
> >>
> >> f2))
> >>
> >>
> >>
> >>
> >>
> >> (define r1 (foo/s (λ ([x : Integer]) (format "~a" x
> >>
> >>
> >>
> >> The type of r1 is correctly deduced as:
> >>
> >>
> >>
> >> - : (-> (Foo Integer) (Foo String) (Foo String))
> >>
> >> #
> >>
> >>
> >>
> >> However, if I slightly change the struct Foo and do the same, like this:
> >>
> >>
> >>
> >> #lang typed/racket
> >>
> >>
> >>
> >> (struct (a) Foo ([val : (-> a a)]))
> >>
> >>
> >>
> >> (: foo/s (All (a b)
> >>
> >>   (-> (-> a b)
> >>
> >>   (-> (Foo a)
> >>
> >>   (Foo b)
> >>
> >>   (Foo b)
> >>
> >> (define (foo/s f)
> >>
> >>   (λ ([f1 : (Foo a)]
> >>
> >>   [f2 : (Foo b)])
> >>
> >> f2))
> >>
> >>
> >>
> >>
> >>
> >> (define r1 (foo/s (λ ([x : Integer]) (format "~a" x
> >>
> >>
> >>
> >> Now, r1 has this type:
> >>
> >>
> >>
> >> - : (-> (Foo Nothing) (Foo String) (Foo String))
> >>
> >> #
> >>
> >>
> >>
> >> Surprisingly (Foo Integer) has changed to (Foo Nothing)! Is this a
> possible bug in the type system? Or, may be I'm missing something?
> >>
> >>
> >>
> >> Thanks!
> >>
> >>
> >>
> >> --
> >>
> >> You received this message because you are subscribed to the Google
> Groups "Racket Users" group.
> >>
> >> To unsubscribe from this group and stop receiving emails from it, send
> an email to racket-users...@googlegroups.com.
> >>
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> >
> > --
> > You received this message because you are subscribed to the Google
> Groups 

[racket-users] Readtable - allowing pipes (bars) in operator

[Martin Janiczek]

Hello everybody,

is there a way to tell the `(read)` function not to interpret `|` as an "copy 
this verbatim" delimiter?

What I want to do is:
(read "(|| a b)") ;=> '(|| a b)
(read "(<| a b)") ;=> '(<| a b)
etc. - allow `|` as a symbol.

I know about readtables - dabbled with them before and they seem like the right 
tool for the job. But in this case, my last attempt was:

(make-readtable (current-readtable)
  #\|
  'terminating-macro
  read-as-symbol)

and I couldn't get the `read-as-symbol` function right. Also experimented with 
`read-accept-bar-quote` parameter but no dice.

Any help/pointers?

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