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0 pointsmrkeen5y ago0 comments

> What is this ungodly mess?

    type API = "polls"                                           :> Get  '[JSON] [Poll]
          :<|> "polls" :> Capture "question_id" Int              :> Get  '[JSON]  Poll
          :<|> "polls" :> Capture "question_id" Int :> "results" :> Get  '[JSON]  PollResults

Delightful :D

  The API is the route "/polls" accessed via GET, returning a list of Polls in JSON format
          or the route "/polls/question_id" where question_id is an Int, accessed via GET, returning a Poll in JSON format
          or the route "/polls/question_id/results" where question_id is an Int, accessed via GET, returning PollResults in JSON format

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3 comments · 2 top-level

runeks5y ago· 1 in thread

Since we’re discussing syntax I’d like to question the necessity of the tick preceding [JSON].

Could we leave out this tick given that the kind of this parameter is [*]?

pyrale5y ago

For reasons that are not easy to explain, no.

[JSON] and '[JSON] have different meanings. Here, '[JSON] does not refer to a list of json files, but to a type-level list of the mimetypes that can be returned. You could see '[JSON, PNG] instead, which would make no sense in the context of a list type declaration.

The genius of Servant is that the DSL doesn't require you to know how '[] is implemented and why it's different from [], you just have to know the DSL.

quickthrower25y ago

Yep as soon as you make it look like natural language, compilers magically become intelligent and context aware readers of prose, not the old-school pedantic expectors of syntax rules.

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