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
We use NoContent to signify an empty response nowadays. This commit
replaces all occurences of () with NoContent so that all packages use
the new semantics.
We've previously used functions in the Router type to provide
information for subrouters. But this accesses the Requests too
early, and breaks sharing of the router structure in general,
causing the Router or large parts of the Router to be recomputed
on every request.
We now do not use functions anymore, and properly compute all
static parts of the router first, and gain access to the request
only in Delayed.
This also turns the code used within Delayed into a proper monad
now called DelayedIO, making some of the code using it a bit
nicer.
* Improves how Routers are built, in particular via
the `choice` smart constructors. Static lookups are
now used more often.
* We now have test cases making sure that certain
routers have the same structure.
* The router structure can now be visualized for debugging
purposes as a tree. The new functions `layout` and
`layoutWithContext` do this.
