derived BNF-like grammar to specify syntax

grammar.md

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+## Lexical syntax ##
+
+    OPEN-PAREN   :=   '('
+    
+    CLOSE-PAREN  :=   ')'
+    
+    OPEN-SQUARE  :=   '['
+    
+    CLOSE-SQUARE :=   ']'
+    
+    OPEN-CURLY   :=   '{'
+    
+    CLOSE-CURLY  :=   '}'
+    
+    WHITESPACE   :=   ' '  |  '\t'  |  '\n'  |  '\r'
+    
+    COMMENT      :=   ';'  ???
+    
+    STRING       :=   '"'  ???  '"'
+    
+    CONSTANT     :=   '*'  ???  '*'
+    
+    BOOLEAN      :=   'true'  |  'false'
+    
+    SYMBOL       :=   ???
+    
+    NUMBER       :=   ???
+    
+    HASH         :=   '#!'  ???
+
+
+## Grammar ## ([example](http://docs.python.org/2/reference/grammar.html))
+
+    Hy           :=  HASH  |  COMMENT  |  WHITESPACE  |  Expression
+
+    Expression   :=  OPEN-PAREN  Operator  Args  Close-Paren
+    
+    Operator     :=  ???
+    
+    Args         :=  Value(*)
+    
+    List         :=  OPEN-SQUARE  Value(*)  CLOSE-SQUARE
+    
+    Map          :=  OPEN-CURLY  ( Value  Value )(*)  CLOSE-CURLY
+    
+    Value        :=  STRING  |  CONSTANT  |  BOOLEAN  |  SYMBOL  |  NUMBER  |  Expression  |  List  |  Map
+