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Show 8 Uli The L«nau«<ita ^EnVironmant A. Explanation of th» FormmlimB ümed Syntax Two formalisna are used to describe the syntax of FLEXt A variant of BMF (Backus Normal Forn) (with , factoring) and the syntax-chart aethod developed by Burrpughs Corporation. Uo] For an example, let us describe a FLEX identifier. in Englishi An identifier is a text string of arbitrary length starting with a letter and thereafter composed of either letters of numbers• T *•» ^ident>« i-<letter> |<ideiit> in wirs <tetter> |<ident><nuinber> In Chert: IE£E3 A box says that the construct is defined elsewhere on the chart; a lozenge indicates that this is the definition. Semantics and Pragmatics The semantics and pragmatics of FLEX will be largely described in English (drawing heavily from accepted notions in mathematics and computer science). Whenever possible, FLEX, itself, will be used for description and, indeed, this is done in the SCRIBE chapter where FLEX is presented written in itself. . iMrTtti** |
