HttpCall.fs

open System.Net.Http
open System.Net.Http.Json

type Rate = { PLN: double }

type ApiResponse =
    { Amount: double
      Base: string
      Date: string
      Rates: Rate }

let result =
    async {
        let client = new HttpClient()

        let! result =
            client.GetFromJsonAsync<ApiResponse>("https://api.frankfurter.app/latest?amount=10.99&from=USD&to=PLN")
            |> Async.AwaitTask

        printfn $"10.99 in USD is {result.Rates.PLN} in PLN"
    }

result |> Async.RunSynchronously