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Update macro-expansion.md

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Tbkhi 2024-03-11 09:18:44 -03:00 committed by nora
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@ -561,7 +561,7 @@ pattern for matching a `macro` definition as `$( $lhs:tt => $rhs:tt );+`. In
other words, a `macro_rules` definition should have in its body at least one other words, a `macro_rules` definition should have in its body at least one
occurrence of a token tree followed by `=>` followed by another token tree. occurrence of a token tree followed by `=>` followed by another token tree.
When the compiler comes to a `macro_rules` definition, it uses this pattern to When the compiler comes to a `macro_rules` definition, it uses this pattern to
match the two token trees per rule in the definition of the `macro`, _thereby match the two token trees per the rules of the definition of the `macro`, _thereby
utilizing the `macro` parser itself_. In our example definition, the utilizing the `macro` parser itself_. In our example definition, the
metavariable `$lhs` would match the patterns of both arms: `(print metavariable `$lhs` would match the patterns of both arms: `(print
$mvar:ident)` and `(print twice $mvar:ident)`. And `$rhs` would match the $mvar:ident)` and `(print twice $mvar:ident)`. And `$rhs` would match the