On 11/9/21 23:03, Marc Nieper-Wißkirchen wrote:
arantees the R7RS behavior for its built-in procedures, it cannot guarantee this for all extension libraries.
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>     Similarly, when someone implements (set! x 0) to return zero or two values, I'll be happy to retract my claim that in practice R6RS procedures that are defined to return unspecified values in practice return exactly one value.
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> Neither do I know of an implementation that doesn't return exactly one value. But I would prefer if zero values were returned because it would help a lot to catch a number of errors earlier.

In Kawa set! returns 0 values, as does set-car! and many others.
More specifically, the return type is void, and the return values is #!void, which is
equivalent to (values).
--
	--Per Bothner
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