b0b02f1948
We define `ServerT (NamedRoutes api) m` as `api (AsServerT m)`, so that the server of an record-defined API is a record of handlers. The implementation piggy backs on the instance for “vanilla” servant types with `(:<|>)`, using the `GServantProduct` for converting backd and forth between the record / vanilla servers. The main difficulty is that GHC needs to know that this operation is legit, which can be expressed as the fact that: ``` GToServant (Rep (ServerT (NamedRoutes api))) m ~ ServerT (GToServant (Rep (api AsApi))) m ``` plus a few additional constraints. This is easy enough for `route`, as we know that `m ~ Handler`. But in the case of `hoistServerWithContext`, the two involved monads are unknown ; in other words, this constraint needs to hold `forall m.` Switching `-XQuantifiedConstraints` on is not sufficient, as our constraints involve type families (`Rep` and `ServerT`). Our trick is to use an intermediary typeclass, `GServer`, as a provider of evidence (in the form of a `Dict`) that our constraints are indeed satisfied for a particular monad. The only instance of `GServer` is defined along with it, so it is practically invisible to users. |
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| .. | ||
| greet.hs | ||
| greet.md | ||
| README.md | ||
greet.hsshows how to write a simple webservice, run it, query it with automatically-derived haskell functions and print the (generated) markdown documentation for the API.greet.mdcontains the aforementioned generated documentation.