The Story of Haskell at IMVU(chadaustin.me)

  let upload _ = async.Return()
  let takePhoto i = async.Return [|0uy|]
  // i stands for "photo i of N", a required parameter for our workflow

  let runSequence n =
    async {
      let rec runSequenceRec (framesSoFar: byte[] list) =
        async {
          if framesSoFar.Length = n then
            return List.rev framesSoFar
          else
            let! bytes = takePhoto framesSoFar.Length
            do! upload bytes
            return! runSequenceRec (bytes::framesSoFar)
        }
      return! runSequenceRec []
    }

  let runSequence' n =
    async {
      let frames = System.Collections.Generic.List<byte[]>()
      for i = 0 to n do
        let! bytes = takePhoto i
        do! upload bytes
        frames.Add bytes
      return frames
    }

  let forNAsync f n =
    let rec runOnce (soFar: _ list) =
      async {
        if soFar.Length = n then
          return List.rev soFar
        else
          let! result = f soFar.Length
          return! runOnce (result::soFar)
      }
    async.ReturnFrom(runOnce [])

  let runOneShot i =   
    async {
      let! bytes = takePhoto i
      do! upload bytes
      return bytes
    }

  let runSequence'' = forNAsync runOneShot

  let runSequence''' n =
    async {
      let frames = System.Collections.Generic.List<byte[]>()
      for i = 0 to n do
        let! bytes = runOneShot i
        frames.Add bytes
      return frames
    }

  let runOneShot'''' i (frames: System.Collections.Generic.List<byte[]>) = 
    async {
      let! bytes = takePhoto i
      do! upload bytes
      frames.Add bytes
    }

  let runSequence'''' n =
    async {
      let frames = System.Collections.Generic.List<byte[]>()
      for i = 0 to n do
        do! runOneShot'''' i frames
      return frames
    }