F# Making Rest Calls

A simple F# app to call a rest service.

In this sample we call a rest web service to the location of the international space station.

We will use the HttpClient to call the rest service async

 let getISSLocation =
    async {
         let url = "http://api.open-notify.org/iss-now.json"
         use httpClient = new System.Net.Http.HttpClient()
         let! location = 
         getAsync httpClient url
         let data = Json.deserialize<ISSLocation> location
         printfn "Returned Locatiom: %s" location

let getAsync (client:HttpClient) (url:string) = 
    async {
          let! response = client.GetStringAsync(url) |> Async.AwaitTask
          return response

To make an async call you need the async block. The let! tells it to wait until the result is returned.

I use the NuGet Package FSharp.JSON to deserialize the data into this class

type location =
        longitude : string
        latitude : string

type ISSLocation =
        timestamp : int
        message : string
       iss_position : location

You can find a sample here