EffFs

EffFsは、SRTP を用いた F# の Effect System ライブラリです。

SideEffect や Dependency を静的に解決することができます。

• wraikny/EffFs - GitHub
• EffFs - NuGet Gallery

Example

open EffFs

type RandomInt = RandomInt of int with
  static member Effect(_) = Eff.marker<int>

type Logging = Logging of string with
  static member Effect(_) = Eff.marker<unit>

let inline foo() = eff {
  let! a = RandomInt 100
  do! Logging (sprintf "%d" a)
  let b = a + a
  return (a, b)
}

let rand = System.Random()

type Handler = Handler with
  static member inline Value(_, x) = x

  static member inline Handle(RandomInt a, k) =
    rand.Next(a) |> k

  static member inline Handle(Logging s, k) =
    printfn "[Log] %s" s; k()

foo()
|> Eff.handle Handler
|> printfn "%A"


// example output
(*
[Log] 66
(66, 132)
*)