This functionality has now been integrated into idris-vim. This repository will not receive updates and will only remain for compatibility purposes.
This is a few modifications on https://github.com/Twinside/vim-haskellConceal that I use for working with idris in vim. It should replace text with nicer-looking unicode characters when applicable, making your code look all pretty and math-like. An example of the changes this makes is above. To install this you can either install the included idris.vim file to ~/.vim/after/syntax or just point your favorite package manager at this repo.