Re: [racket-users] strange behaviour of procedure partitions

[Gustavo Massaccesi]

I can reproduce this error in
Welcome to DrRacket, version 6.11 [3m].
Language: racket [custom]; memory limit: 2048 MB.

but only if I use this configuration:

[X] No debugging or profiling

[   ] Populate compiled directories (I didn't try enabling this)
[??] Preserve stacktrace (error with or without this option)
[X] Enforce constant definitions

Gustavo



On Sun, Nov 12, 2017 at 6:57 PM, Jos Koot  wrote:
> I have downloaded and installed "Welcome to DrRacket, version
> 6.11.0.2--2017-11-12(b54ea8c5b1/a) [3m].",
> but the problem still remains.
> I have Windows 7 premium home.
> Thanks, Jos
>
> 
> From: Jens Axel Søgaard [mailto:jensa...@soegaard.net]
> Sent: zondag 12 november 2017 21:21
> To: Jos Koot; Racket Users
> Subject: Re: [racket-users] strange behaviour of procedure partitions
>
>
> søn. 12. nov. 2017 kl. 19.54 skrev Jos Koot :
>>
>> Hi
>>
>> In the definitions window of DrRacket:
>>
>> #lang racket
>> (require (only-in math/number-theory partitions))
>> (partitions 0)
>> (partitions 0)
>>
>> Runs ok,
>> but after running,
>> typing (partitions 0) in the interactions window
>> gives the following error:
>>
>> define-values: assignment disallowed;
>>  cannot re-define a constant
>>   constant: lifted.0
>
>
> Have you tried it in a version of Racket using the new expander?
>
> Just a hunch based on: https://github.com/racket/datalog/issues/6
>
>
>> The error does not show up when I comment out
>> the two lines (partitions 0) in the definitions window
>> and rerun before typing (partitions 0) in the interactions window.
>> I suppose this is a bug.
>>
>> The error does not occur when replacing
>> #lang racket
>> by
>> #lang typed/racket
>>
>> It is very well possible that I don't correctly require
>> from a typed module into an untyped one.
>> Should be possible, no?
>>
>> Thanks, Jos
>>
>> --
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>> "Racket Users" group.
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>> email to racket-users+unsubscr...@googlegroups.com.
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>
> --
> --
> Jens Axel Søgaard
>
> --
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RE: [racket-users] strange behaviour of procedure partitions

[Jos Koot]

I have downloaded and installed "Welcome to DrRacket, version 
6.11.0.2--2017-11-12(b54ea8c5b1/a) [3m].",
but the problem still remains.
I have Windows 7 premium home.
Thanks, Jos

  _  

From: Jens Axel Søgaard [mailto:jensa...@soegaard.net] 
Sent: zondag 12 november 2017 21:21
To: Jos Koot; Racket Users
Subject: Re: [racket-users] strange behaviour of procedure partitions



søn. 12. nov. 2017 kl. 19.54 skrev Jos Koot :




Hi 

In the definitions window of DrRacket: 

#lang racket 
(require (only-in math/number-theory partitions)) 
(partitions 0) 
(partitions 0) 

Runs ok, 
but after running, 
typing (partitions 0) in the interactions window 
gives the following error: 

define-values: assignment disallowed; 
 cannot re-define a constant 
  constant: lifted.0 




Have you tried it in a version of Racket using the new expander?

Just a hunch based on: https://github.com/racket/datalog/issues/6



The error does not show up when I comment out 
the two lines (partitions 0) in the definitions window 
and rerun before typing (partitions 0) in the interactions window. 
I suppose this is a bug. 

The error does not occur when replacing 
#lang racket 
by 
#lang typed/racket 

It is very well possible that I don't correctly require 
from a typed module into an untyped one. 
Should be possible, no? 

Thanks, Jos 



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-- 

-- 
Jens Axel Søgaard


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Re: [racket-users] strange behaviour of procedure partitions

[Jens Axel Søgaard]

søn. 12. nov. 2017 kl. 19.54 skrev Jos Koot :

> Hi
>
> In the definitions window of DrRacket:
>
> #lang racket
> (require (only-in math/number-theory partitions))
> (partitions 0)
> (partitions 0)
>
> Runs ok,
> but after running,
> typing (partitions 0) in the interactions window
> gives the following error:
>
> *define-values: assignment disallowed;*
> * cannot re-define a constant*
> *  constant: lifted.0*
>
>
Have you tried it in a version of Racket using the new expander?

Just a hunch based on: https://github.com/racket/datalog/issues/6


The error does not show up when I comment out
> the two lines (partitions 0) in the definitions window
> and rerun before typing (partitions 0) in the interactions window.
> I suppose this is a bug.
>
> The error does not occur when replacing
> #lang racket
> by
> #lang typed/racket
>
> It is very well possible that I don't correctly require
> from a typed module into an untyped one.
> Should be possible, no?
>
> Thanks, Jos
>
> --
> 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.
>
-- 
-- 
Jens Axel Søgaard

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[racket-users] strange behaviour of procedure partitions

[Jos Koot]

Hi

In the definitions window of DrRacket:

#lang racket
(require (only-in math/number-theory partitions))
(partitions 0)
(partitions 0)

Runs ok,
but after running,
typing (partitions 0) in the interactions window
gives the following error:

define-values: assignment disallowed;
 cannot re-define a constant
  constant: lifted.0

The error does not show up when I comment out
the two lines (partitions 0) in the definitions window
and rerun before typing (partitions 0) in the interactions window.
I suppose this is a bug.

The error does not occur when replacing
#lang racket
by
#lang typed/racket

It is very well possible that I don't correctly require
from a typed module into an untyped one.
Should be possible, no?

Thanks, Jos

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Re: [racket-users] where does DrRacket get its environment variables on OS X?

[Greg Hendershott]

People hit this using GUI Emacs on macOS -- and use the
`exec-path-from-shell` Emacs Lisp package:

  https://github.com/purcell/exec-path-from-shell




Ever find that a command works in your shell, but not in Emacs?

This happens a lot on OS X, where an Emacs instance started from the
GUI inherits a default set of environment variables.

This library solves this problem by copying important environment
variables from the user's shell: it works by asking your shell to
print out the variables of interest, then copying them into the Emacs
environment.




The source is <270 lines of Emacs Lisp -- of which >200 is comments
and boilerplate.

Maybe someone could make an equivalent DrRacket plugin and provide it
as a Racket package?

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[racket-users] catching a contract violation in a unit test with check-exn

[Tim Hanson]

hi,

As part of something I'm working on I want to convert a stream of values 
into a stream of pairs of values, e.g.

  1 2 3 4

becomes
  (1 2) (3 4)

The following seems to work fine:

(define (pairwise-stream astream)
  (if (stream-empty? astream)
  empty-stream
  (stream-cons
   (cons
(stream-first astream)
(stream-first (stream-rest astream)))
   (pairwise-stream
(stream-rest (stream-rest astream))

but I'd like my 2nd or 3rd test to detect a problem with a stream of odd 
length and haven't figured out how yet. Here's my attempt (lengths 0 and 2 
work fine, length 1 shows a contract violation, but my test doesn't detect 
it):

(check-equal?
 (stream->list
  (pairwise-stream empty-stream))
 (stream->list empty-stream))

; hmmm, how to detect this correctly?
;(check-exn
; exn:fail:contract?
; (stream-first
;  (pairwise-stream (stream-cons 1 empty-stream

(check-equal?
 (stream->list (pairwise-stream (stream-cons 1 (stream-cons 2 
empty-stream
 (stream->list (stream-cons (cons 1 2) empty-stream)))

I'd be grateful for advice.

Cheers,

Tim

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