( source dest -- )
{
  value| source dest size buffer |
  {
    {
      [ "W" file.open to dest ] is open-dest
      [ "R" file.open to source ] is open-source
      [ open-dest open-source ]
    } is open-files
    {
      [ source file.size to size ] is obtain-size
      [ size malloc to buffer ] is allocate-buffer
      [ obtain-size allocate-buffer ]
    } is create-buffer
    [ source dest and 0 <> ] is check
    [ open-files create-buffer check ]
  } is prepare
  [ source buffer size file.read drop ] is read-source
  [ dest buffer size file.write drop ] is write-dest
  [ source file.close dest file.close ] is close-files
  [ prepare [ read-source write-dest close-files ] ifTrue ]
} is copy-file