BNF Notation

• Importance
  • standard way to define programming language syntax
  • good background for later part of course

• Stands for either "Backus Normal Form" or "Backus-Naur Form"

• Includes two sets:
  • terminals are symbols in the language being defined, e.g. while, for, =, [.
  • nonterminals are used to talk about the language, and are enclosed in angle brackets, e.g. <assignment statement>, <declaration>.

• There are only two metasymbols
  • ::= means "is defined as"
  • | means "or"

• BNF uses recursion heavily