https://twitter.com/7shi/status/748094400606023680 をちょっといじってみる

ListReaderBuilder.fs

type ListReaderBuilder() =
  member this.Bind(g, f) = function (x::xs) -> (f (g x)) xs | _ -> ()
  member this.Return(_) = fun _ -> ()
let listReader = ListReaderBuilder()
 
let test = listReader {
  do! printfn "%d"
  do! printfn "%d"
}

test [1;2;3]
printfn "---"
test [4]

output.txt

1
2
---
4