Fix servant-docs code sample in README

[szg251]

I found a few problems in the code sample of servant-docs, so I fixed them for later users:

• toSample function no longer exists
• DocQueryParam needs a ParamKind argument
• RQBody should be ReqBody
• added implicit imports for better readability

Related issue:
#1212

[fisx]

Thanks! I opened an issue that takes this yet a little further: #1336

I was going to merge this PR as a good step in the right direction, but when I copied your Main.hs over the example file:

example/greet.hs:87:13: error:
    • No instance for (Servant.Docs.Internal.HasDocs
                         (Servant.API.Verbs.Verb
                            'http-types-0.12.3:Network.HTTP.Types.Method.DELETE 200 '[] ()))
        arising from a use of ‘docs’
    • In the expression: docs testApi
      In an equation for ‘greetDocs’: greetDocs = docs testApi
   |
87 | greetDocs = docs testApi

What commit did you test this against?

[szg251]

I am sorry, I didn't notice that! My IDE auto-formatted the code, but I didn't want to introduce more changes than necessary, so I removed the format related changes, that's when these lines must have slipped out of existence.

I guess the real goal here would be to have running examples somewhere in the repository, and then testing them, and generating README based on them in CI. Is that a good solution? (I am still relatively inexperienced with OSS and library development)

[fisx]

I guess the real goal here would be to have running examples somewhere in the repository, and then testing them, and generating README based on them in CI. Is that a good solution?

Yes, that's what I was trying to suggest in #1336. I think it may be as simple as copying the code from the README.md to the existing eamples/greet.hs, but I haven't looked at it in details. When I tried, the diff looked non-trivial.

Anyway, your readme compiles and runs, the one from master doesn't, so this is an improvement. :)

If you like, you can give #1336 a shot now, or any time.

Thanks for the fix!