Upgrading to Ubuntu 15.04 Vivid Vervet Alpha

When using a rolling release GNU/Linux distribution, you've to constantly update your packages and odd you may face some stability issues due to certain packages. However, I've been using Fedora Rawhide for the past few months without major issues. Hence, I've decided to upgrade my Ubuntu 14.10 to 15.04 even though it still in alpha release.

Distribution upgrade using the so-called manual or brute force way.
sudo apt-get update; sudo apt-get dist-upgrade
sudo sed 's/utopic/vivid/g' -i /etc/apt/sources.list
sudo apt-get update; sudo apt-get dist-upgrade

Off course, the distro upgrade would not be that smooth as there are many legacy repository that you'll need to remove or disable in in either the /etc/apt/sources.list file or /etc/apt/sources.list.d folder.

Using the Ubuntu source list generator, below is the most minimal repository URLs after some trial and errors as some of the repository components (Restricted and Multiverse) does not exists. Hence, only main component is used.
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://download.nus.edu.sg/mirror/ubuntu/ vivid main universe
deb http://download.nus.edu.sg/mirror/ubuntu/ vivid-updates main universe
deb http://download.nus.edu.sg/mirror/ubuntu/ vivid-security main universe
deb http://download.nus.edu.sg/mirror/ubuntu/ vivid-proposed main universe

Note that we're also include those from pre-release updates (vivid-proposed) since I opted to get the most latest bleeding edge packages. If you want manually update those pre-release updates, you can set a different priority to this repository.

Make sure this file /etc/apt/preferences.d/proposed-updates exists with this content:
Package: *
Pin: release a=vivid-proposed
Pin-Priority: 400

And run this command to selectively select those packages to be upgraded from vivid-proposed repository.
$ sudo aptitude -t vivid-proposed

MzScheme No More

As I was reading "Teach Yourself Scheme in Fixnum Days", which surprisingly have its own Wikipedia page, and eager to try out the Scheme tutorial in my recently upgraded Ubuntu 15.04 and noticed that that MzScheme is not available anymore in the repository.

$ sudo apt-get install mzscheme
Reading package lists... Done
Building dependency tree      
Reading state information... Done
Package mzscheme is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'mzscheme' has no installation candidate

Checking the MzScheme official site, I've learned that MzScheme is the core virtual machine of the PLT Scheme and PLT Scheme has been renamed to Racket to show that it is a descendant instead of variant of Scheme.

Searching the repository for any Racket packages.
$ sudo apt-cache search ^racket
plt-scheme - Racket Programming Environment (transitional package)
racket - extensible programming language in the Scheme family
racket-common - extensible programming language in the Scheme family (shared files)
racket-doc - extensible programming language in the Scheme family (documentation)

Since PLT Scheme is a transitional package, installing it will let us install Racket as well.
$ sudo apt-get install plt-scheme
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  racket racket-common racket-doc
The following NEW packages will be installed:
  plt-scheme racket racket-common racket-doc
0 upgraded, 4 newly installed, 0 to remove and 98 not upgraded.
Need to get 64.2 MB of archives.
After this operation, 390 MB of additional disk space will be used.
Do you want to continue? [Y/n]

To test our installation.
$ mzscheme 
Welcome to Racket v6.1.
> 

Let's try our first hello world example in Scheme.
;The first program

(begin
  (display "Hello, World!")
  (newline))

Execute the program from console.
$ mzscheme -r hello.scm 
Hello, World!