Idris on Ubuntu

For Ubuntu "raring" users (the April 2013 release) that don't grok such magicks and just want step-by-step instructions of the dark ritual (for installing Idris 0.9.9):

• type "repositories" into the Unity searchy thingey (you know, the Start menu wannabe).
• Choose the only option, this should lead you to a config-y window.
• Find the correct tab that lists repositories, and click "Add"

The magic incantation to paste into the box is:

deb http://llvm.org/apt/raring/ llvm-toolchain-raring main

now you can go to a terminal and:

sudo apt-get update && sudo apt-get install llvm-3.3

While you're at it, also be sure to:

sudo apt-get install libgc-dev

Then I believe a fresh raring install (assuming you've already managed to get the latest haskell platform) should be able to:

PATH=/usr/lib/llvm-3.3/bin:$PATH cabal install idris

without further complaint. (The PATH environment variable is necessary so that the correct version of llvm is found, so that the Cabal LLVM library compiles. Unfortunately, the default LLVM on Raring is still 3.2, so without this line it will fail.)