This commit introduces a new type-level combinator, `WithRoutingHeader`.
It modifies the behaviour of the following sub-API, such that all endpoint
of said API return an additional routing header in their response.
A routing header is a header that specifies which endpoint the
incoming request was routed to.
Endpoint are designated by their path, in which `Capture'` and
`CaptureAll` combinators are replaced by a capture hint.
This header can be used by downstream middlewares to gather
information about individual endpoints, since in most cases
a routing header uniquely identifies a single endpoint.
Example:
```haskell
type MyApi =
WithRoutingHeader :> "by-id" :> Capture "id" Int :> Get '[JSON] Foo
-- GET /by-id/1234 will return a response with the following header:
-- ("Servant-Routed-Path", "/by-id/<id::Int>")
```
To achieve this, two refactorings were necessary:
* Introduce a type `RouterEnv env` to encapsulate the `env` type
(as in `Router env a`), which contains a tuple-encoded list of url
pieces parsed from the incoming request.
This type makes it possible to pass more information throughout the
routing process, and the computation of the `Delayed env c` associated
with each request.
* Introduce a new kind of router, which only modifies the RouterEnv, and
doesn't affect the routing process otherwise.
`EnvRouter (RouterEnv env -> RouterEnv env) (Router' env a)`
This new router is used when encountering the `WithRoutingHeader`
combinator in an API, to notify the endpoints of the sub-API that they
must produce a routing header (this behaviour is disabled by default).
This commit introduces a `CaptureHint` type, which is passed as an extra
argument to the `CaptureRouter` and `CaptureAllRouter` constructors for
the `Router'` type.
`CaptureHint` values are then used in `routerLayout`, to display the
name and "type" of captured values (single or list), instead of just
"<capture>" previously.
N.B.:
Because the `choice` smart constructor for routers can aggregate
`Capture` combinators with different capture hints, the `Capture*Router`
constructors actually take a *list* of `CaptureHint`, instead of a
single one.
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
- Introduce SourceT, which is simple variant of "correct `ListT`".
There are another variants possible (like in `streaming`),
but I'm not sure there's much real difference.
- Introduce `Codensity`. There's a flag if people don't want to depend
on `kan-extensions`.
- `StreamGenerator` and `ResultStream` are both `SourceT`.
`Stream` combinator in `servant-client` uses `Codensity` for CPS.
- Add servant-machines, servant-conduit, servant-pipes
- Add streaming cookbook: just code, no explanations.
- Add a script to run streaming 'benchmarks'
In case that a sub-server doesn't support the content-type specified
in the request invoke `delayedFail` instead of `delayedFailFatal` in
order to give the chance to other sub-servers to handle the request.
- WIP: pending http-api-data release
- TODO: remove MIN_VERSION_http_types
- There have been 3 major releases of http-types:
- 0.10 change name of variable
- 0.11 lowercase escaped URIs
- 0.12 uppercase escaped URIs
- It's easier for us to support only latest, migration from 0.9/0.10 to 0.12
is trivial for the downstream. 0.11 may cause semantic (non-type-error) breakage somewhere.
Also allow lens-4.16, remove MIN_VERSION_http_types conditionals, and
update `stack.yaml`
Changes Header, ReqBody and QueryParam to take a modifier list.
Resolves https://github.com/haskell-servant/servant/issues/856
ResponseHeader story turns to be somewhat ugly, but it can be made
elegant when https://github.com/haskell-servant/servant/issues/841 is
implemnted, then we can omit HList aka Header Heterogenous List
implementation.
- servant-server changes:
Writing server side intepretations is quite simple using
`unfoldRequestArgument`, which makes Header and QueryParam look quite
the same.
`ReqBody` cannot be easily made optional with current design (what that
would mean: No Content-Type Header?), so that dimensions isn't used
there.
- Add HasLink for all the rest ComprehensiveAPI combinators
- Add 'tricky' Header', QueryParam' endpoints to ComprehensiveAPI
- servant-docs: Quick'n'dirty implementation. Don't use modifiers information (yet).
For uniformity of Enter.
Previously, `ServerT Raw m ~ Application`. Seems reasonable, but has the
unfortunate consequence of making `Enter` useless for `Raw` routes.
With this change `Tagged m Application` is retagged by `Enter`.
