binary selectors ambiguity and space
helbig at Lehre.BA-Stuttgart.DE
Sat May 13 16:35:55 UTC 2006
you found out:
>$- except as first binary character is forbidden in Scanner>>xBinary
>Thus '1 +- 2' will scan successive tokens (1) (#+) (#-) (2).
This complies with the syntax diagrams in the Purple Book (this page is left
blank in my edition of the Blue Book):
The minus character must not be the second character of a binary selector. Why?
What's so bad about a binary selector like #/- or #\- ? (These selectors would
mean Integer division rounded towards minus infinity, as opposed to the accepted
binary selectors #/+ and #\+, which is, suprise, Integer division rounded
towards plus infinity.)
Weniger, aber besser.
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