[F#] Volapük dictionary converter

Convert.fsx

// http://personal.southern.edu/~caviness/Volapuk/Misc/eng-vol.htm
// http://personal.southern.edu/~caviness/Volapuk/Misc/vol-eng.htm

// https://gist.github.com/7shi/de072cd867f3899aa285bc9343110bff
#load "XmlParser.fsx"

open System
open System.IO
open System.Text
open XmlParser

do
    use sr = new StreamReader("eng-vol.htm")
    use sw = new StreamWriter("eng-vol.txt")
    let mutable src = ""
    let line = ref ""
    let readLine() =
        line := sr.ReadLine()
        not <| isNull !line
    while readLine() do
        if (!line).StartsWith "&nbsp;" then
            use xp = new XmlParser(!line)
            if xp.Read() then
                let t = (fromEntity xp.Text).TrimStart()
                if t.StartsWith "-" then
                    src <- src + " | " + t.[1..].TrimStart()
                else
                    sw.WriteLine src
                    src <- t
            while xp.Read() do
                src <- src + fromEntity xp.Text
        else
            if src <> "" then
                sw.WriteLine(src)
                src <- ""
            if (!line).StartsWith "<b>" then
                use xp = new XmlParser(!line)
                while xp.Read() do
                    src <- src + fromEntity xp.Text

do
    use sr = new StreamReader("vol-eng.htm")
    use sw = new StreamWriter("vol-eng.txt")
    let line = ref ""
    let readLine() =
        line := sr.ReadLine()
        not <| isNull !line
    while readLine() && !line <> "</CENTER>" do ()
    while readLine() && !line <> "<hr>" do
        if (!line).StartsWith "<p><center>" || !line = "<br>" then () else
        use xp = new XmlParser(!line)
        while xp.Read() do
            sw.Write(fromEntity xp.Text)
            if xp.Tag = "br" then sw.WriteLine()