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#time "on"
#load "Bootstrap.fsx"

open System
open Akka.Actor
open Akka.Configuration
open Akka.FSharp
open Akka.TestKit

// #Using Actor

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namespace MyNamespace

type IMyInterface =
    abstract GetValue: unit -> string

type MyRecord = 
    { MyField1: int
      MyField2: string }
    interface IMyInterface with
        member x.GetValue() = x.MyField2

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// Rather than use [<DefaultValue>], define a default record.
type MyRecord = {
  field1 : int
  field2 : int
}

let defaultRecord1 = { field1 = 0; field2 = 0 }
let defaultRecord2 = { field1 = 1; field2 = 25 }

// Use the with keyword to populate only a few chosen fields

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open System.Runtime.CompilerServices

[<Extension>]
type public FSharpFuncUtil = 
    
    [<Extension>] 
    static member ToFSharpFunc<'a> (func:System.Func<'a>) = fun () -> func.Invoke()

    [<Extension>] 
    static member ToFSharpFunc<'a,'b> (func:System.Converter<'a,'b>) = fun x -> func.Invoke(x)

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open Microsoft.FSharp.Reflection

let toString (x:'a) = 
    match FSharpValue.GetUnionFields(x, typeof<'a>) with
    | case, _ -> case.Name

let fromString<'a> (s:string) =
    match FSharpType.GetUnionCases typeof<'a> |> Array.filter (fun case -> case.Name = s) with
    |[|case|] -> Some(FSharpValue.MakeUnion(case,[||]) :?> 'a)
    |_ -> None

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#r "~/packages/Sendgrid.5.1.0/lib/SendGridMail.dll"
#r "~/packages/SendGrid.SmtpApi.1.2.1/lib/net40/SendGrid.SmtpApi.dll"

open System
open System.Collections.Generic
open System.Net
open System.Net.Mail
open SendGrid

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open System
open System.Net

// exception handling in async using Async.Catch
let fetchAsync (name, url:string) =
    async {
        let uri = new System.Uri(url)
        let webClient = new WebClient()
        let! html = Async.Catch (webClient.AsyncDownloadString(uri))
        match html with

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open System.Threading.Tasks

[<AutoOpen>]
module Async =
    let inline awaitPlainTask (task: Task) = 
        // rethrow exception from preceding task if it fauled
        let continuation (t : Task) : unit =
            match t.IsFaulted with
            | true -> raise t.Exception
            | arg -> ()

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Railway Oriented Programming and F# Result

Full source: https://gist.github.com/mrange/aa9e0898492b6d384dd839bc4a2f96a1

Option<_> is great for ROP (Railway Oriented Programming) but we get no info on what went wrong (the failure value is None which carries no info).

With the introduction F# 4.1 we got Result<_, _> a "smarter" Option<_> as it allows us to pass a failure value.

However, when one inspects the signature of Result.bind one sees a potential issue for ROP:

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module ApiModel where

import Data.Time (ZonedTime(..), parseTimeM, defaultTimeLocale, iso8601DateFormat)

data ReservationRendition = ReservationRendition
  { rDate :: String
  , rName :: String
  , rEmail :: String
  , rQuantity :: Int }
  deriving (Eq, Show, Read)