Finding Java in the registry using F#

find_java.fs

let rec findWorkingJava registryKeys =
    match registryKeys with
    | [] -> ""
    | x::xs ->
        let value = Registry.GetValue(x, "JavaHome", String.Empty)
        match value with
        | null -> findWorkingJava xs
        | _ -> value.ToString()

let findJavaInRegistry registryPath =
    let subKeyPath = sprintf @"Software\JavaSoft\%s" registryPath
    use javaRegKey = Registry.LocalMachine.OpenSubKey(subKeyPath)
    let javaSubKeys = 
        match javaRegKey with
        | null -> []
        | key ->
            key.GetSubKeyNames() |> Array.map (fun x -> (sprintf @"%s\%s" (javaRegKey.ToString()) (x.ToString()))) |> Array.toList

    findWorkingJava javaSubKeys

// this scans a list of things and tries to find a registry path that has Java
let rec scanForJava searchList =
    match searchList with
    | [] -> ""
    | x::xs ->
        let path = findJavaInRegistry x
        if not <| String.IsNullOrEmpty path then path
        else scanForJava xs
        
/// Attempt to discover the Java path on this local system.
/// It tries to use environment variables (JAVA_HOME) and the local filesystem
/// if this is a windows machine.
let private DiscoverJavaPath () =
    let envPath = environVar "JAVA_HOME"
    let systemPath = scanForJava ["Java Runtime Environment"; "Java Development Kit"]

    if not <| String.IsNullOrEmpty envPath then envPath @@ "bin" @@ "java.exe"
    elif not <| String.IsNullOrEmpty systemPath then systemPath @@ "bin" @@ "java.exe"
    else String.Empty