Haskell Extensions.ipynb

It might be interesting not to look at the % of files using a given pragma, but the % of projects using a given pragma: it might be that only certain files in a project use the pragma, but to work on the project you will sooner or later need to know that extension.

Also, you can define "always-on" extensions in your cabal file. This is used extensively. So the number of .hs files that use/need an extension is much higher than those that declare it as a pragma in the file itself.