On 1 May 2011 23:49, Aaron W. Hsu <[email protected]> wrote: > On Sat, 30 Apr 2011 20:30:14 -0400, Malcolm Tredinnick > <[email protected]> wrote: > > > Archaeological expeditions were similarly unrewarding — the current > > description of numbers has remained more or less unchanged since at > > least R4RS and the 1@1 style is not mentioned. One can kind of > > reverse-engineer the requirements from the hints in the description of > > (make-polar ...) and (angle ...) on page 29, but even there it doesn't > > explicitly tie the polar form to the x@y syntax! > > The R6RS has a grammar description of the datum syntax for numbers which > includes the @ and normal complex forms. I don't know if any of this has > been used in the current report, but previous standards have provided > information on it. The TSPL also contains a more general description, but > my understanding was that this syntax was purposefully fairly vague. >
If you mean the grammar specification in the <complex> production on page 13 of the R6RS report, then that's the same as in R7RS draft 1 and is similar all the way back to at least R4RS. However, the problem is that it's only describing a bunch of symbols, not semantics. That's not enough information for an implementer or for somebody wanting to verify correct behaviour. Nowhere is it mentioned that this *is* the polar form, for example, let alone whether the number after the "@" is interpreted as radians or degrees or even possibly pineapples. You cannot come to a recent Scheme report and get any understanding of what 1@2 actually means. If that's not the section you mean, could you provide a little specificity so I can see what I'm overlooking? I spent more than a little while looking through all the older reports and couldn't find the missing explanation of semantics. Regards, Malcolm
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