* bumped cabal-version field
Cabal supports two types of licenses, native and SPDX, which can be seen here hackage.haskell.org/package/Cabal-3.6.2.0/docs/Distribution-Types-PackageDescription.html#v:licenseRaw
Several packages use BSD-3-Clause as a license, in conjonction with cabal-version: >=1.10 which cabal parses as Right (UnknownLicense "BSD-3").
If I change teh cabal-version to cabal-version: 2.2 , cabal correctly identifdies the license License (ELicense (ELicenseId BSD_3_Clause)).
* changed license from cabal to spdx format
aka BSD3 -> BSD-3-Clause: next cabal may deprecate the old format
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.
Currently there is no way for Servant users to customize formatting of
error messages that arise when combinators can't parse URL or request
body, apart from reimplementing those combinators for themselves or
using middlewares.
This commit adds a possibility to specify custom error formatters
through Context.
Fixes#685
