tiny typo

pull/6/head
Matthew Butterick 7 years ago
parent 18c6119a26
commit c7601a8964

@ -683,7 +683,7 @@ A @deftech{pattern} is one of the following:
Because their underlying meanings are the same, the symbolic token identifier ends up being a notational convenience for readability inside a grammar pattern. Typically, the literal string @racket["FOO"] is used to connote ``match the string @racket["FOO"] exactly'' and the symbolic token identifier @racket[FOO] specially connotes ``match any token of type @racket['FOO]''. Because their underlying meanings are the same, the symbolic token identifier ends up being a notational convenience for readability inside a grammar pattern. Typically, the literal string @racket["FOO"] is used to connote ``match the string @racket["FOO"] exactly'' and the symbolic token identifier @racket[FOO] specially connotes ``match any token of type @racket['FOO]''.
You @bold{cannot} use the literal string @racket["error"] as a terminal in a grammar, because it's reserved for @tt{brag}. You can, however, adjust your lexer to package it inside a token structure — say, @racket[(token ERROR "error")] — and then use the symbolic token identifier @racket[ERROR] in the grammar to match this token structure. You @bold{cannot} use the literal string @racket["error"] as a terminal in a grammar, because it's reserved for @tt{brag}. You can, however, adjust your lexer to package it inside a token structure — say, @racket[(token 'ERROR "error")] — and then use the symbolic token identifier @racket[ERROR] in the grammar to match this token structure.
} }
@item{a @tech{rule identifier}} @item{a @tech{rule identifier}}

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