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Date: Tue, 11 Apr 2006 18:22:37 -0400 From: Marc Feeley <feeley@iro.umontreal.ca> I'm not sure I understand your point. I'm advocating for a colon suffix. SRFI 42 uses a colon prefix on identifiers (which by the way is illegal in R5RS except for a lone colon). So keyword objects using a colon suffix syntax do not hinder in any way SRFI 42 or any R5RS compliant code, but a colon prefix syntax does. My point is just that changing the meaning of a colon as either a prefix or a suffix will break some existing R5RS-compliant code. According to R5RS section 7.1.1, a trailing colon is most certainly allowed in identifiers: <identifier> ---> <initial> <subsequent>* | <peculiar identifier> <initial> ---> <letter> | <special initial> <special initial> ---> ... | `:' | ... <subsequent> ---> <initial> | <digit> | <special subsequent> Since `:' is a special initial, it is also an initial, and transitively also a subsequent; it may therefore be used at the end of an identifier, according to the rule for <identifier>. I know that some code has used colon suffixes on identifiers (for example the withdrawn iota: function in SRFI 1), but there are very few uses of this and it is not portable anyway so I don't think this argument has much weight. Not portable? Only to Scheme systems that are already non-compliant. Of the Schemes I use regularly, all allow colon suffixes in identifiers.