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4 Examples

The rule:

any-symbol: symbol
          ;

is equivalent to

any-symbol: symbol
            ( $1 )
          ;

which, if it matched the string ‘"A"’, would return

( "A" )

If this rule were used like this:

%token <punctuation> EQUAL "="
…
assign: any-symbol EQUAL any-symbol
        ( $1 $3 )
      ;

it would match ‘"A=B"’, and return

( ("A") ("B") )

The letters ‘A’ and ‘B’ come back in lists because ‘any-symbol’ is a nonterminal, not an actual lexical element.

To get a better result with nonterminals, use , to splice lists in like this:

%token <punctuation> EQUAL "="
…
assign: any-symbol EQUAL any-symbol
        ( ,$1 ,$3 )
      ;

which would return

( "A" "B" )