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BNF
nonterm
BNF-seq
BNF-group
optional
kleenestar
kleeneplus
kleenerange
BNF-alt
BNF-etc

4.6 BNF Grammars

The scribble/bnf library provides utilities for typesetting grammars.

See also racketgrammar.

(BNF prod ...)  table?
  prod : (cons element? (listof element?))
Typesets a grammar table. Each production starts with an element (typically constructed with nonterm) for the non-terminal being defined, and then a list of possibilities (typically constructed with BNF-seq, etc.) to show on separate lines.

(nonterm pre-content ...)  element?
  pre-content : any/c
Typesets a non-terminal: italic in angle brackets.

(BNF-seq elem ...)  element?
  elem : element?
Typesets a sequence.

(BNF-group pre-content ...)  element?
  pre-content : any/c
Typesets a group surrounded by curly braces (so the entire group can be repeated, for example).

(optional pre-content ...)  element?
  pre-content : any/c
Typesets an optional element: in square brackets.

(kleenestar pre-content ...)  element?
  pre-content : any/c
Typesets a 0-or-more repetition.

(kleeneplus pre-content ...)  element?
  pre-content : any/c
Typesets a 1-or-more repetition.

(kleenerange n m pre-content ...)  element?
  n : any/c
  m : any/c
  pre-content : any/c
Typesets a n-to-m repetition. The n and m arguments are converted to a string using (format "~a" n) and (format "~a" m).

(BNF-alt elem ...)  element?
  elem : element?
Typesets alternatives for a production’s right-hand side to appear on a single line. The result is normally used as a single possibility in a production list for BNF.

A string to use for omitted productions or content.