Compared to modules, units are cumbersome to use. The only use case where you are forced to use units is where the dependency graph has a “diamond”. And with a little care it is a situation that often can be avoided.

Prior to the introduction of modules, units were in more wide-spread use. Now almost everyone uses modules. So not exactly legacy - but close.

Is there a standard way to shuffle a list? Picking a random permutation…

In python I’d say from random import shuffle x = [[i] for i in range(10)] shuffle(x)

@stefan.kruger Yes. Use shuffle!

bah

Why can’t I find these things?

@stefan.kruger In case you don’t know about it, the search box in the Racket docs is very useful for that sort of thing: https://docs.racket-lang.org/search/index.html?q=shuffle

It also links to combinations if you search for “powerset.”

Hey @mflatt, just a heads up that I’ve been getting segfaults from the Racket gui system on the latest version of mac os x.

The specific error being:

CGContextRef->C: argument is not non-null `CGContextRef' pointer
  argument: #f
  context...:
   /Users/leif/racket/racket/collects/ffi/unsafe.rkt:1364:12
   /Users/leif/rsrc/gui/gui-lib/mred/private/wx/cocoa/dc.rkt:117:9: send-arg203
   /Users/leif/rsrc/gui/gui-lib/mred/private/wx/common/backing-dc.rkt:79:4: on-backing-flush method in backing-dc%
   /Users/leif/rsrc/gui/gui-lib/mred/private/wx/cocoa/dc.rkt:113:0: do-backing-flush
   /Users/leif/rsrc/gui/gui-lib/mred/private/wx/cocoa/canvas.rkt:357:5: paint-or-queue-paint method in .../wx/cocoa/canvas.rkt:271:3
   /Users/leif/rsrc/gui/gui-lib/mred/private/wx/cocoa/canvas.rkt:69:2
about to suspend in atomic mode
[1]    33885 abort      ./plt-games

(Also from DrRacket and any other gui program)

But the ‘goblet’ plt game seems to trigger the error the quickest.

Not sure if this is just a problem with my machine though.

Let me know your versions and I’ll try on my machine

@spdegabrielle honestly master.

But I suspect 7.3 would have the same issue.

I can check that now.

@leif Which version of macOS

Oh, the latest one, mojave I think?

Ya, it looks like mojave, 10.14.4

(Sorry, macOS isn’t really my primary OS at this point, so I’m a bit out of the loop if there’s something newer.)

When using a “vertical” slider, it is very squished. Not sure what I’m doing wrong.

(define frame (new frame%
                   [label "Example"]
                   [width 300]))

(define slider (new slider%
                     [label "Slider"]
                     [parent frame]
                     [min-value 0]
                     [max-value 100]
                     [init-value 50]
                     [style '(vertical)]))

(send frame show #t)

@spdegabrielle Hmm…it looks like when I use the 7.3 distribution, it stops segfaulting. Weird.

@leif Do you want me to build from master to reproduce? or is this a DrDr option?

@travis.hinkelman sorry for slow response. I can’t get a vertical slider at all - it just renders as a squashed horizontal.

#lang racket/gui
(define frame (new frame%
                   [label "Example"]
                   [width 600]
                   [height 600]))
(define hp (new vertical-pane% [parent frame]
                [min-width 200]
                [min-height 200]))
(define slider (new slider%
                    [label "Slider"]
                    [parent hp]
                    [min-value 0]
                    [max-value 100]
                    [init-value 50]
                    [min-width 200]
                    [min-height 200]
                    [vert-margin 10]
                    [horiz-margin 10]
                    [style '(horizontal)]))

(send frame show #t)

I want the slider value on the right (which is oddly created by using vertical for style).

I’m still confused by no vertical , but let me look at getting the label on the right

@spdegabrielle Eh. Honestly, its probably not worth it. I can’t find a single other person who can reproduce it, so I suspect there’s something odd with my macOS install.

Thanks for offering though. :slightly_smiling_face:

@leif your version number was lower than mine; I’m on 10.14.5 (18F132)

@leif I believe you wrote 10.14.4

@leif I saw that crash today, too. I was running one of the GL games and figured it was specific to that, but didn’t yet investigate. Racket crashed reliably, CS didn’t. Will investigate more as soon as I can.

@mflatt cool, thanks.w

and @spdegabrielle thanks for checking that.

@travis.hinkelman #lang racket/gui (define fish% (class object% [init parent val] (super-new) (define hp (new horizontal-pane% [parent parent])) (define slider (new slider% [label "Slider"] [parent hp] [min-value 0] [max-value 100] [init-value val] [style '(horizontal plain)])) (define label (new message% [label (format "~a" val) ] [parent hp])) )) (define frame (new frame% [label "Example"] [width 300] [height 300])) (define charlie (new fish% [parent frame] [val 55])) (send frame show #t)

@travis.hinkelman This is a way to put the label on the right.

Thanks. It’s nice to know that there is a relatively straightforward workaround. I started toying around with that simple slider example when I saw this Reddit post: https://www.reddit.com/r/Racket/comments/cew4ws/ui_layout_question/

I’ve pushed a change that should avoid the crash. I have no idea why it only started happening now or why it happens more for you.