Building RESTful Web Services

We can expose simple REST web services with the help of the combinator mapJson. The mapJson uses the default BCL JSON serializer DataContractJsonSerializer.

open Suave
open Suave.Json
open System.Runtime.Serialization

[<DataContract>]
type Foo =
  { [<field: DataMember(Name = "foo")>]
    foo : string }

[<DataContract>]
type Bar =
  { [<field: DataMember(Name = "bar")>]
    bar : string }

startWebServer defaultConfig (mapJson (fun (a:Foo) -> { bar = a.foo }))

ademar@nascio:~$ curl -X POST -d '{"foo":"xyz"}' http://localhost:8083/ -w "\n"
{"bar":"xyz"}

Or you can bring your own JSON serializer like Chiron:https://github.com/xyncro/chiron

type A = 
  { a : int }
  static member ToJson (x : A) =
    Json.writer "a" x.a

Json.format (Json.serialize { a = 42 })
val it = """{"a":42}"""

let app =
  GET >=> path "/test"
  >=> OK (UTF8.bytes it)
  >=> setMimeType "application/json; charset=utf-8"