Icon is a general-purpose language with special features for string scanning. If has some object oriented features but no modules or exception s. It has a primitive Unix interface. Expressions that fail are used in lieu of Booleans. Data backtracking is supported by a reversible assignment .
Icon also has co-expressions, which can be explicitly resumed at any time.
See also Ibpag2 . FTP , MS-DOS FTP . When an icon is clicked on, some action is performed such as opening a directory or aborting a file transfer. Icons are usually stored as bitmap s.