on "module: identifier already imported from a different source"

[Daniel Bastos]

I'm getting "module: identifier already imported from a different
source" when I require these two modules.

(require math/number-theory)
(require racket/list)

I want factorize from math/number-theory and remove-duplicates from racket/list.

I've seen old messages about this error, but they seemed involved with
the full-fledged Racket, while I'm using ISL+ in DrRacket. I decided
to try some things out of HtDP and ended up getting into this trouble.

I don't want the full-fledged Racket because I like to use
check-expect in DrRacket and I seem to get along better with the
student languages error messages.

Solutions such as (require (rename ... ) don't work for me because I'm
speaking ISL+ where my options seem to me these below. (ASL doesn't
seem to expand on it.)

library-require = (require string)
| (require (lib string string ...))
| (require (planet string package))

Perhaps you could suggest me to leave the student languages sometimes
when playing with Racket by showing me how I could get some equivalent
thing to check-expect.

At some point I should move to full-fledged Racket. I suppose after
HtDP I should read another book. Perhaps Realm of Racket?

Thank you.

[Jens Axel Søgaard]

Hi Daniel,

The problems is that math/number-threory and racket/list

both export an function named permutations.

You are right that rename-in or prefix-in could be used to 

fix the problem in "full" Racket. In order to handle the

situation in ISL+ I suggest to make an extra file:

File: "no-conflicts.rkt"

    #lang racket

    (provide (all-from-out math/number-theory)

             (all-from-out racket/list))

    (require math/number-theory)

   (require (except-in racket/list permutations))

And then in the ISL+ file write (require "no-conflicts.rkt").

/Jens Axel

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[Philip Blair]

I don't believe there is a way to do what you are looking to do within
ISL+. To import *just* those two things in full-fledged Racket, one
would do (you may or may not already know this):
(require (only-in math/number-theory factorize))
(require (only-in racket/list remove-duplicates))

The problem is that the (only-in ...) form is not provided in ISL. In
addition, the above two lines would only *both* be required if you were
using #lang racket/base; using #lang racket automatically includes
racket/list.

That aside, it would seem that you must either advance to full Racket or
revisit your approach to the HtDP problem. I personally would suggest
the latter; I worked through all of HtDP last fall and never ran into a
problem like this :)

[Matthias Felleisen]

On Jun 30, 2015, at 8:23 AM, Daniel Bastos <dba...@toledo.com> wrote:

> At some point I should move to full-fledged Racket. I suppose after
> HtDP I should read another book. Perhaps Realm of Racket?

When you have mastered a good part of HtDP, you should move on to Realm.
-- Matthias