The file also states that "Mio will be released as part of GHC 7.8.1", which is scheduled around October if I recall correctly. Neat
https://github.com/byrongibson/scripts/blob/master/install/h...
Tons of advantages to doing it that way, including the ability to easily maintain multiple versions of both GHC and Platform on the same system and swap between them with a single command. Also doesn't clutter up /usr/local/ with binaries not managed by apt or dpkg.
More generally, update-alternatives is a godsend for Stable users. It's like RVM or RBENV in the Ruby world - lets you install and manage multiple versions of the same platform and easily swap between them with a single command, including the system version from repos if you want. It frees you from out of date software in the repos while still providing a system to manage the complexities of it all.
From https://plus.google.com/u/0/111990768169655655719/posts/Se5e...
> Cabal is a package manager that by default compiles packages either to a system database (if invoked as root/admin) or a per-user database. Since Haskell code is very often fussy about exact version numbers, and because Cabal offers essentially no way to uninstall packages, this is very painful. Cabal-dev is a front-end to Cabal that gives you per-directory repositories: suddenly conflicts go away, and you can remove packages by deleting the directory's repository and reinstalling everything again. It's a kludge, but it is very helpful.
Cabal-dev: https://github.com/creswick/cabal-dev
---Postscript
Or in stronger terms: http://comments.gmane.org/gmane.comp.lang.haskell.libraries/...
> I would say, "You should never mutate your user or global package database" and recommend using cabal-dev. The way cabal-install does destructive updates is evil. In particular, it likes to mutate your global or user package database. You run the risk of building something and then breaking it later by mutating its dependencies.