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... should be a peculiar identifier
At the last R*RS meeting the syntactic extension committee was
strongly encouraged to come up with a proposal that provided the
functionality of extend-syntax. Ellipsis is fundamental to that
functionality, and extend-syntax uses the standard ellipsis notation
in a way the many find highly satisfying. Yet according to the R3RS
syntax, ... IS NOT AN IDENTIFIER. Thus the option of providing
extend-syntax as an extension of the standard syntax is closed (unless
the property that programs parse as data is forfeited, which no one
wants to see). I've tried to think of a presently legal identifier
that could serve in place of ..., but without luck. Compatibility
with the existing extend-syntax is also worth something, though not
The syntactic category <peculiar identifier> has already been provided
to make exceptions of + and -. The problem could be fixed by simply
adding ... to the list. This was considered and voted down at
Brandeis, but at that time the community of extend-syntax users was
much smaller and the feeling that some sort of syntactic extension
mechanisms belonged in Scheme had much less support than it does now.
I think we should reconsider this issue now so the syntactic extension
committee isn't faced with an awkward problem in the future.
If consensus can be reached over the net in next the couple of months, it
could even improve the IEEE standard. Comments?