[ nested swap
    nested swap join ]  is compose ( g f --> [ )

  ( ----- demonstration ----- )

 ( create a named nest -- equivalent to a function )

  [ 2 * ]               is double  (   n --> n )

  ( "[ 4 + ]" is an unnamed nest
               -- equivalent to a lambda function. )

  ( "quoting" a nest with ' puts it on the stack
    rather than it being evaluated. "do" evaluates
    the top of stack.                              )

  19   ' double   ' [ 4 + ]   compose do echo