Feature Request: Run code blocks

[andrewthad]

In the colonnade library, in the Colonnade.Encoding, I use doctest. This causes some of the code examples to end up uglier than they could have. For example (in the fromMaybe docs):

>>> :{
>>> let owners :: [(Person,Maybe House)]
>>> owners =
>>> [ (Person "Jordan" 18, Nothing)
>>> , (Person "Ruth" 25, Just (House Red 125000))
>>> , (Person "Sonia" 12, Just (House Green 145000))
>>> ]
>>> :}

However, this is unsightly, and I would never expect anyone to want to run it from ghci. I would much rather write this as:

    owners :: [(Person,Maybe House)]
    owners =
      [ (Person "Jordan" 18, Nothing)
      , (Person "Ruth" 25, Just (House Red 125000))
      , (Person "Sonia" 12, Just (House Green 145000))
      ]

I know that doctest's main goal is to compile things that would be run in ghci. But, being able to run code blocks would go a long way in making documentation more readable.

My (probably bad) take on a solution would be to add a flag for supporting code blocks. If this were enabled, some sketchy heuristic-based algorithm could turn a code block into an equivalent ghci let-binding before handing it to ghci. I would be willing to give this a try, but I'd also really appreciate any feedback on the idea.

[andrewthad]

I'm still interested in trying to do this. Can anyone provide feedback on the approach I outlined or comment on the likelihood of this being merged in if I wrote in?

[kindaro]

@andrewthad Wait a second, but you could already use multiline ghci commands and omit the starting >>> everywhere but in the first line. You still need it to be a comment though. Is this not enough?

Unfortunately, it does not work with properties. There is an issue #131 about it.

[andrewthad]

Eventually, I realized that was possible, and that's the convention that I've adopted in my libraries. I still think that it wastes space, but it's an acceptable workaround.