nonassoc in yacc code example

Example: nonassoc in yacc

%left, %right and %nonassoc, defines how yacc will solve repetition of operators 
In case you have:

	$ 1 + 2 + 3

both operators have the same precedence level ( they are the same :) ), 
in this case yacc can solve:

// using %left

	$ (1 + 2) + 3

or:
// using %right

	$ 1 + (2 + 3)

and finally:
//using %nonassoc

	$ 1 + 2 + 3 
is considered illegal and a syntax error!