# [racket] the Numbers grammar

Thanks! I'll fix the documentation.
At Thu, 9 Aug 2012 02:07:43 +0100, milo arvidsson wrote:
>* I've been studying the numbers grammar in section 1.3.3 of the Racket
*>* reference and I think I've spotted a few mistakes:
*>*
*>* 1. <exact-complex_n> allows the imaginary part of an exact complex
*>* number to be signed given that an exact rational may be signed:
*>*
*>* <exact-integer_n> ::= [<sign>] <unsigned-integer_n>
*>* <exact-rational_n> ::= <exact-integer_n> / <unsigned-integer_n>
*>* <exact-complex_n> ::= <exact-rational_n> <sign> <exact-rational_n> i
*>*
*>* The rule allows exact complex numbers like this one: 1/2+-3/4i
*>*
*>* but ...
*>*
*>* >1/2+-3/4i
*>* 1/2+-3/4i: undefined;
*>* cannot reference undefined identifier
*>*
*>* 2. The three alternatives in <inexact-simple_n> should be unsigned
*>* given that <inexact-unsigned_n> uses <inexact-normal_n> which uses
*>* <inexact-simple_n>. But since exact integers may be signed, the second
*>* alternative in <inexact-simple_n> may be signed:
*>*
*>* <inexact-simple_n> ::= [<exact-integer_n>] . <digits#_n>
*>*
*>* 3. <inexact-normal_n> allows # in an exponent:
*>*
*>* <digits#_n> ::= <digit_n>+ #*
*>* ‹inexact-normal_n› ::= <inexact-simple_n> [<exp-mark_n> [<sign>] <digits#_n>]
*>*
*>* but ...
*>*
*>* >3.14e+87#
*>* 3.14e+87#: undefined;
*>* cannot reference undefined identifier
*>*
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