peg-1-parse-pt2.fs

    | Sequence x ->
        let rec parseList lst off =
            seq {
                if List.isEmpty lst then ()
                else
                    match parse off <| List.head lst with
                    | (Unmatched, _) as y -> yield y
                    | (y, z) -> yield (y, z)
                                yield! parseList (List.tail lst) z
            }
        
        let s = List.ofSeq <| parseList x offset 
        if List.exists (function | (Unmatched, _) -> true | _ -> false) s then (Unmatched, offset)
        else (Production <| List.map fst s, snd <| List.maxBy snd s)
    | Choice x ->
        let rec parseList lst =
            if List.isEmpty lst then (Unmatched, offset)
            else
                match parse offset <| List.head lst with
                | (Unmatched, _) -> parseList <| List.tail lst
                | y -> y
        
        parseList x