Inline documentation of function params

[heath]

It could potentially be nice to have inline documentation of function parameters...

Maybe it is better practice to create a type alias for each and every parameter, but sometimes it's more convenient to add inline documentation using this style of documentation:

foo : bar -- documentation for the bar param
   -> baz -- documentation for the baz param
   -> qux

Haddock does a nice job of generating documentation for functions with this method, see e.g.:
https://hackage.haskell.org/package/bytestring-0.10.8.1/docs/Data-ByteString.html#v:breakSubstring

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.