Document CaptureHint in Capture[All]Router (#1634)

Co-authored-by: Nicolas BACQUEY <nicolas.bacquey@tweag.io>
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nbacquey 2022-12-08 09:20:53 +01:00 committed by GitHub
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2 changed files with 20 additions and 1 deletions

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@ -13,6 +13,7 @@ Compatibility with GHC 9.4, see [PR #1592](https://github.com/haskell-servant/se
- Add `MonadFail` instance for `Handler` wrt [#1545](https://github.com/haskell-servant/servant/issues/1545)
- Support GHC 9.2 [#1525](https://github.com/haskell-servant/servant/issues/1525)
- Add capture hints in `Router` type for debug and display purposes [PR #1556] (https://github.com/haskell-servant/servant/pull/1556)
0.19
----

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@ -28,9 +28,12 @@ import Servant.Server.Internal.ServerError
type Router env = Router' env RoutingApplication
-- | Holds information about pieces of url that are captured as variables.
data CaptureHint = CaptureHint
{ captureName :: Text
-- ^ Holds the name of the captured variable
, captureType :: TypeRep
-- ^ Holds the type of the captured variable
}
deriving (Show, Eq)
@ -54,10 +57,21 @@ data Router' env a =
-- for the empty path, to be tried in order
| CaptureRouter [CaptureHint] (Router' (Text, env) a)
-- ^ first path component is passed to the child router in its
-- environment and removed afterwards
-- environment and removed afterwards.
-- The first argument is a list of hints for all variables that can be
-- captured by the router. The fact that it is a list is counter-intuitive,
-- because the 'Capture' combinator only allows to capture a single varible,
-- with a single name and a single type. However, the 'choice' smart
-- constructor may merge two 'Capture' combinators with different hints, thus
-- forcing the type to be '[CaptureHint]'.
-- Because 'CaptureRouter' is built from a 'Capture' combinator, the list of
-- hints should always be non-empty.
| CaptureAllRouter [CaptureHint] (Router' ([Text], env) a)
-- ^ all path components are passed to the child router in its
-- environment and are removed afterwards
-- The first argument is a hint for the list of variables that can be
-- captured by the router. Note that the 'captureType' field of the hint
-- should always be '[a]' for some 'a'.
| RawRouter (env -> a)
-- ^ to be used for routes we do not know anything about
| Choice (Router' env a) (Router' env a)
@ -101,6 +115,10 @@ choice router1 router2 = Choice router1 router2
data RouterStructure =
StaticRouterStructure (Map Text RouterStructure) Int
| CaptureRouterStructure [CaptureHint] RouterStructure
-- ^ The first argument holds information about variables
-- that are captured by the router. There may be several hints
-- if several routers have been aggregated by the 'choice'
-- smart constructor.
| RawRouterStructure
| ChoiceStructure RouterStructure RouterStructure
deriving (Eq, Show)