reitit/doc/advanced/configuring_routers.md

# Configuring Routers

Routers can be configured via options. The following options are available for the `reitit.core/router`:

| key             | description
|-----------------|-------------
| `:path`         | Base-path for routes
| `:routes`       | Initial resolved routes (default `[]`)
| `:data`         | Initial route data (default `{}`)
| `:spec`         | clojure.spec definition for a route data, see `reitit.spec` on how to use this
| `:syntax`       | Path-parameter syntax as keyword or set of keywords (default #{:bracket :colon})
| `:expand`       | Function of `arg opts => data` to expand route arg to route data (default `reitit.core/expand`)
| `:coerce`       | Function of `route opts => route` to coerce resolved route, can throw or return `nil`
| `:compile`      | Function of `route opts => result` to compile a route handler
| `:validate`     | Function of `routes opts => ()` to validate route (data) via side-effects
| `:conflicts`    | Function of `{route #{route}} => ()` to handle conflicting routes
| `:exception`    | Function of `Exception => Exception ` to handle creation time exceptions (default `reitit.exception/exception`)
| `:meta-merge`   | Function of `left right => merged` to merge route-data (default `meta-merge.core/meta-merge`)
| `:update-paths` | Sequence of Vectors with elements `update-path` and `function`, used to preprocess route data
| `:router`       | Function of `routes opts => router` to override the actual router implementation