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https://github.com/lemaetech/wtr

HTTP request routing library for OCaml web applications.
https://github.com/lemaetech/wtr

ocaml router webapp

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HTTP request routing library for OCaml web applications.

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README

        

# Wtr - Well Typed Router

Wtr - A HTTP request routing library for OCaml web applications.

[Documentation](https://lemaetech.co.uk/wtr/)          [Examples](https://github.com/lemaetech/wtr/tree/main/examples)           [Summer Demo](https://github.com/lemaetech/summer/blob/main/examples/echo_server.ml)

## Overview

`wtr` is a HTTP request router for OCaml web applications.

- It is trie based so route matching is efficient and fast.
- Route handlers are type-checked during compilation.
- Supports matching and capturing URI path components, eg `/home/about/:int`.
- Supports matching and capturing URI query parameters, eg `/home/about?q=:int&q1=hello`.
- Supports matching HTTP methods, eg `GET, POST, PUT, HEAD, DELETE` etc.
- Supports converting captured URI components to OCaml and custom user defined data types.
- `%routes` ppx implements a DSL to allow you to easily specify HTTP uri.
- combinatros based approach to specifying routes.

## Wtr Demo

```ocaml
# #require "wtr, wtr-ppx";;
```

```ocaml
module Fruit = struct
type t = Apple | Orange | Pineapple

let t : t Wtr.arg =
Wtr.arg "fruit" (function
| "apple" -> Some Apple
| "orange" -> Some Orange
| "pineapple" -> Some Pineapple
| _ -> None )
end

let about_page = "about page"
let prod_page i = "Int page. number : " ^ string_of_int i
let float_page f = "Float page. number : " ^ string_of_float f
let contact_page nm num = "Contact. Hi, " ^ nm ^ ". Num " ^ string_of_int num
let product1 name id q = Format.sprintf "Product1 %s. Id: %d. q = %b" name id q
let product2 name id = Format.sprintf "Product2 %s. Id: %d." name id
;;
let fruit_page = function
| Fruit.Apple -> "Apples are juicy!"
| Orange -> "Orange is a citrus fruit."
| Pineapple -> "Pineapple has scaly skin"

let faq category_id _ =
let category_name =
match category_id with
| 1 -> "products"
| 2 -> "insurance"
| 3 -> "returns"
| _ -> "unknown"
in
"FAQ page for category : " ^ category_name

let router =
Wtr.router
[ {%routes| get,post,head,delete ; /home/about/ |} about_page
; {%routes| head,delete ; /home/:int/ |} prod_page
; {%routes| get,post ; /home/:float/ |} float_page
; {%routes| get; /contact/*/:int |} contact_page
; {%routes| get; /product/:string?section=:int&q=:bool |} product1
; {%routes| get; /product/:string?section=:int&q1=yes |} product2
; {%routes| get; /fruit/:Fruit |} fruit_page
; {%routes| GET; /faq/:int/** |} faq ]

let p () =
Printf.printf "\n====Router Match Results====\n" ;
[ Wtr.match' `GET "/home/100001.1/" router
; Wtr.match' `DELETE "/home/100001/" router
; Wtr.match' `GET "/home/about/" router
; Wtr.match' `GET "/product/dyson350?section=233&q=true" router
; Wtr.match' `GET "/product/dyson350?section=2&q=false" router
; Wtr.match' `GET "/product/dyson350?section=2&q1=yes" router
; Wtr.match' `GET "/product/dyson350?section=2&q1=no" router
; Wtr.match' `GET "/fruit/apple" router
; Wtr.match' `GET "/fruit/orange" router
; Wtr.match' `GET "/fruit/pineapple" router
; Wtr.match' `GET "/fruit/guava" router
; Wtr.match' `GET "/faq/1/" router
; Wtr.match' `GET "/faq/1/whatever" router
; Wtr.match' `GET "/faq/2/whateasdfasdfasdf" router ]
|> List.iteri (fun i -> function
| Some s -> Printf.printf "%3d: %s\n" (i + 1) s
| None -> Printf.printf "%3d: None\n" (i + 1) );;
```

## Demo Output

```ocaml
# p () ;;
====Router Match Results====
1: Float page. number : 100001.1
2: Int page. number : 100001
3: about page
4: Product1 dyson350. Id: 233. q = true
5: Product1 dyson350. Id: 2. q = false
6: Product2 dyson350. Id: 2.
7: None
8: Apples are juicy!
9: Orange is a citrus fruit.
10: Pineapple has scaly skin
11: None
12: FAQ page for category : products
13: FAQ page for category : products
14: FAQ page for category : insurance
- : unit = ()
```