Add ability to embed runnable code snippets in content

[beerendlauwers]

Having the ability to embed runnable code snippets in content would enhance the usefulness of many types of content. Ideally, you would have a "default" GHC version that runs the code, guaranteed, and the ability to select a different GHC version to check if it still works.

Embedding the code snippet in a simple <div class="haskell-code-snippet"> would also allow validation of any code snippets to see if they typecheck (actually running them on the validation server sounds like a bad idea). Bonus points if this is done with multiple GHC versions, and that information is fed back into the snippet (perhaps with CSS classes added to the snippet: ghc-8-0 ghc -7-10-3).

[codexp]

isn't it already done? but I can't find docs on how to use it...