proper clean of .net solution

CleanSolution.fs

    open System.IO
    let deleteBinAndObj (dirInfo: DirectoryInfo) =
        let bin = dirInfo.GetDirectories("bin")
        for dir in bin do
            if dir.Name.ToLower() = "bin" then
                dir.Delete(true)
        let objDirs = dirInfo.GetDirectories("obj")
        for dir in objDirs do
            if dir.Name.ToLower() = "obj" then
                dir.Delete(true)

    let rec recursiveClean dir =
        deleteBinAndObj dir
        let children = dir.GetDirectories()
        for child in children do
            recursiveClean child

    let clean() =
        let dir = Directory.GetCurrentDirectory() |> DirectoryInfo
        recursiveClean dir