absolute path converts path into an absolute path.

split path splits path into a dirname and a basename if possible.

Examples:

  split ""                = None
  split "/"               = None
  split "/hello"          = Some ("/", "hello")
  split "/User/name/xxx/" = Some("/User/name", "xxx")
  split "/User/name/xxx"  = Some("/User/name", "xxx")

normalize path removes duplicate path separators and normalizes "." and ".." segments.

Examples:

  normalize ""            = "."
  normalize "/"           = "/"
  normalize "////"        = "/"
  normalize "a//b"        = "a/b"
  normalize "a/./b"       = "a/b"
  normalize "a/../b"      = "b"
  normalize "a/b/../../c" = "c"
  normalize "../a"        = "../a"

join dir file joins the directory name dir with the file name file.