Possible F# Type Inference Bug In Workaround Form

typeInferenceBug.fsx

// NB. to reproduce bug, delete the type after the colon

module AST =
  type name = string
  type param = string
  type arg = Number of int | Arg of param

  type Part =
  | Cell of string

module Parser

open AST
open FParsec

let test p str =
  match run p str with 
  | Success(result, _, _) -> printfn "Success: %A %O" result (result.GetType())
  | Failure(errorMsg, _, _) -> printfn "Failure: %s" errorMsg

let proc : ref<(((string * string) list) list)> = ref []

let one : Parser<string,unit> = pstring "1" 
let two : Parser<string,unit> = pstring "2" 

let three : Parser<Part,unit> = pstring "2" |>> fun s->Part.Cell(s)

test one "1"

let pNumberWord = one <|> two |>> fun a->Part.Cell(a)

test pNumberWord "2"

Some of the library specific demos / documentation suggested otherwise. That's good news. Thanks Don! Much appreciated.