[racket-users] Skolelinux / Debian Edu & Racket

[Neil Van Dyke]

It looks like Skolelinux (aka Debian Edu) is used in hundreds of 
schools.  Has anyone looked into making sure it includes a good Racket 
version, in a turn-key way?


https://en.wikipedia.org/wiki/Skolelinux

I haven't used Skolelinux, but I can say that Debian was an early 
innovator in GNU/Linux distributions (e.g., network package system, 
multiple release channels for different stability preferences), has most 
everything packaged for it, is a basis for some other distros (including 
Ubuntu), and does unusually good watchdogging about various openness / 
libre principles.  For these reasons, I almost always use Debian Stable 
on my personal workstations and servers, even though some other distros 
also have some appealing other merits.


Below is a new Skolelinux press release, corresponding to the new Debian 
Stable release.


8<cut-here8<


The Debian Project https://www.debian.org/
Debian Edu / Skolelinux Buster — a complete
Linux solution for your school pr...@debian.org
July 7th, 2019 https://www.debian.org/News/2019/20190707



Do you have to administrate a computer lab or a whole school network?
Would you like to install servers, workstations and laptops which will
then work together? Do you want the stability of Debian with network
services already preconfigured? Do you wish to have a web-based tool to
manage systems and several hundred or even more user accounts? Have you
asked yourself if and how older computers could be used?

Then Debian Edu is for you. The teachers themselves or their technical
support can roll out a complete multi-user multi-machine study
environment within a few days. Debian Edu comes with hundreds of
applications pre-installed, but you can always add more packages from
Debian.

The Debian Edu developer team is happy to announce Debian Edu 10
"Buster", the Debian Edu / Skolelinux release based on the Debian 10
"Buster" release. Please consider testing it and reporting back
() to help us to improve it further.


About Debian Edu and Skolelinux
---

Debian Edu, also known as Skolelinux [1], is a Linux distribution based
on Debian providing an out-of-the box environment of a completely
configured school network. Immediately after installation a school
server running all services needed for a school network is set up just
waiting for users and machines to be added via GOsa², a comfortable web
interface. A netbooting environment is prepared, so after initial
installation of the main server from CD / DVD / BD or USB stick all
other machines can be installed via the network. Older computers (even
up to ten or so years old) can be used as LTSP thin clients or diskless
workstations, booting from the network without any installation and
configuration at all. The Debian Edu school server provides an LDAP
database and Kerberos authentication service, centralized home
directories, a DHCP server, a web proxy and many other services. The
desktop contains more than 60 educational software packages and more are
available from the Debian archive. Schools can choose between the
desktop environments Xfce, GNOME, LXDE, MATE, KDE Plasma and LXQt.

    1: https://wiki.debian.org/DebianEdu


New features for Debian Edu 10 "Buster"
---

These are some items from the release notes for Debian Edu 10 "Buster",
based on the Debian 10 "Buster" release. The full list including more
detailed information is part of the related Debian Edu manual
chapter [2].

  * Official Debian installation images are now available.
  * Site specific modular installation is possible.
  * Additional meta-packages grouping educational packages by school
level are provided.
  * Improved desktop localization for all languages Debian supports.
  * Tool available to ease setting up site specific multi-language support.
  * GOsa²-Plugin Password Management has been added.
  * Improved TLS/SSL support inside the internal network.
  * The Kerberos setup supports NFS and SSH services.
  * A tool to re-generate the LDAP database is available.
  * X2Go server is installed on all systems with profile LTSP-Server.

    2:
https://wiki.debian.org/DebianEdu/Documentation/Buster/Features#New_features_in_Debian_Edu_Buster


Download options, installation steps and manual
---

Separate Network-Installer CD images for 64-bit and 32-bit PCs are
available. Only in rare cases (for PCs older than around 12 years) the
32-bit image will be needed. The images can be downloaded at the
following locations:

  * http://get.debian.org/cdimage/release/current/amd64/iso-cd
  * http://get.debian.org/cdimage/release/current/i386/iso-cd


Alternatively extended BD images (more than 5 GB large) are also
available. It is poss

Re: [racket-users] What's wrong with my code?

[Matthias Felleisen]

With some for/loops in TR you’re out of luck. The expansion are too complex to 
type-check easily. 


> On Jul 7, 2019, at 10:24 AM, 曹朝  wrote:
> 
> This is a simple algorithm for compute the shortest edit distance, it can 
> work with `#lang racket/base`.
> But in Typed Racket, I just got the error message: "insufficient type 
> information to typecheck". I don't know why this code can't pass the type 
> checker.
> Someone can help? Thank you.
> 
> #lang typed/racket/base
> (require math/array)
> 
> (: shortest-edit-distance (-> String String Integer))
> (define (shortest-edit-distance str0 str1)
> (let* ([l0 : Integer (string-length str0)]
>[l1 : Integer (string-length str1)]
>[table : (Mutable-Array Integer) (array->mutable-array (make-array 
> (vector l0 l1) 0))])
>   (for*/last : Integer ([i0 : Integer (in-range l0)]
> [i1 : Integer (in-range l1)])
> (let* ([c0 : Char (string-ref str0 i0)]
>[c1 : Char (string-ref str1 i1)]
>[base : Integer (cond
>  [(and (= i0 0) (= i1 0)) 0]
>  [(= i0 0) (array-ref table (vector i0 (sub1 
> i1)))]
>  [(= i1 0) (array-ref table (vector (sub1 i0) 
> i1))]
>  [else (min (array-ref table (vector i0 (sub1 
> i1)))
> (array-ref table (vector (sub1 i0) 
> i1))
> (array-ref table (vector (sub1 i0) 
> (sub1 i1])]
>[answer : Integer (if (char=? c0 c1) base (add1 base))])
> 
>   (array-set! table (vector i0 i1) answer)
>   answer
> 
> <截屏2019-07-0800.15.13.png>
> 
> 
> 
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> <截屏2019-07-0800.15.13.png>

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