package routes

Routes

This library will help with adding typed routes to OCaml applications.

Users can create a list of routes, and handler function to work on the extracted entities using the combinators provided by the library. To perform URL matching one would just need to forward the URL's path and query to the matcher.

The core library in the current state isn't tied to any particular library or framework. It should be usable in the current state, but the idea would be to provide sub-libraries with tighter integration with the remaining ecosystem. Future work would also include working on client side routing for use with js_of_ocaml libraries like incr_dom or ocaml-vdom.

Example

# #require "routes";;
# open Routes;;
# open Infix;;
# type req = {target: string};;
type req = { target : string; }

# let idx (_ : req) = "root";;
val idx : req -> string = <fun>

# let get_user (id: int) (req : req) = Printf.sprintf "Received request from %s to fetch id: %d" req.target id
val get_user : int -> req -> string = <fun>

# let search_user (name: string) (city : string) (_req : req) = "search for user";;
val search_user : string -> string -> req -> string = <fun>

# let routes =
  with_method [ `GET, idx <$ s "" (* matches the index route "/" *)
  ; `GET, get_user <$> s "user" *> int (* matches "/user/<int>" *)
  ; `POST, search_user <$> s "user" *> str </> str (*  matches "/user/<str>/<str>" *)
  ]
val routes : (req -> string) router = <abstr>

# let req = { target = "/user/12" };;
val req : req = {target = "/user/12"}

# match Routes.match_with_method routes ~target:"/some/url" ~meth:`GET with None -> "No match" | Some r -> r req;;
- : string = "No match"

# match Routes.match_with_method routes ~target:req.target ~meth:`GET with None -> "No match" | Some r -> r req;;
- : string = "Received request from /user/12 to fetch id: 12"

Installation

To use the version published on opam:

opam install routes

For development version:

opam pin add routes git+https://github.com/anuragsoni/routes.git

Example use inside other libraries:

• Httpaf -> example/main.ml

• Opium -> example/opium_example.ml

Related Work

The combinators are influenced by Rudi Grinberg's wonderful blogpost about type safe routing done via an EDSL using GADTs + an interpreted for the DSL.

Also thanks to Gabriel Radanne for feedback and for the blog post showing the technique used in printf like functions.