The [routes|...|] quasi-quoter. Captures use RFC 6570 URI-template syntax — {name} for a single segment, {+name} for a splat — and ?name1&name2 for query-string parameters.

[routes|PostsController
GET    /posts                 PostsAction
GET    /posts/{postId}        ShowPostAction
PATCH  /posts/{postId}        UpdatePostAction
GET    /search?q&page         SearchAction
|]

Query parameters are declared explicitly: each ?name names a record field on the action constructor that the URL carries in the query string. The field's Haskell type determines the shape: plain a is required (missing/unparseable ⇒ 404), Maybe a is optional, [a] collects repeated values (?tags=a&tags=b). Every record field of the action constructor must be covered by either a path capture or a query-param entry — unbound fields fail at splice time with a pointer to the exact fields left over.

Renaming. To map a capture or query-param name to a differently named record field, use the { field = #name } syntax after the action. Works for path captures and query params alike:

GET /ShowPost?id     ShowPostAction { postId = #id }
GET /users/{uid}     ShowUserAction { userId = #uid }

This is the ihp-router (plain-WAI) flavour of the quoter — emits HasPath instances and a per-controller <ctrlLower>Trie binding only. IHP apps use the wrapping quoter from IHP.Router.IHP (re-exported through IHP.Router.DSL), which additionally emits the IHP-flavoured CanRoute instance and lowercase-header webRoutes binding.

Three header forms — all top-level declarations:

1. Single-controller. Uppercase-initial header = controller type.
2. Binding-named (multi-controller). Lowercase-initial header is the name of a binding the splice emits. In ihp-router it carries the per-controller trie values; in IHP it additionally carries the [ControllerRoute app] list for FrontController.controllers.
3. No header. Multi-controller, instances + trie values only.

Path-indexed trie node.

Lookup priority at each node is: literal segment > typed capture > splat. Splat captures consume the remaining path and land on the bundled HandlersByMethod.

Wrap a RouteTrie as a WAI Middleware.

Semantics:

• If the trie matches, the matched handler (a Captures -> Application) runs with the captured path segments and the incoming request.
• If the path matches but the HTTP method does not, a 405 Method Not Allowed response is returned with an Allow header listing the supported methods.
• If neither the path nor a splat matches, the request is handed to the fallback application — which is the standard WAI behaviour when a middleware declines a request.

The middleware is pure with respect to the trie: construction happens at application startup, lookup on every request.

A type that can appear as a URL path segment.

Instances provide a parseCapture for decoding a raw segment bytestring (post-URL-decoding) into a typed value, and renderCapture for the reverse direction when generating URLs via pathTo.

Example:

>>> parseCapture @Int "42"
Just 42

>>> renderCapture (42 :: Int)
"42"

A URL path segment guaranteed to be non-empty.

Useful when a capture must not match an empty string. Plain Text captures happily match "" (the segment between two consecutive slashes); Segment rejects that case, which is often what you want for splat captures or required path pieces.

Type class for types that can be converted to URL paths.

This is used by IHP's routing system to generate URLs for controller actions.

Example:

>>> pathTo UsersAction
"/Users"

>>> pathTo ShowUserAction { userId = "a32913dd-ef80-4f3e-9a91-7879e17b2ece" }
"/ShowUser?userId=a32913dd-ef80-4f3e-9a91-7879e17b2ece"