Marc Feeley scripsit:

> R7RS defines mutation of imported variables as "an error".  This looks
> like a restriction to me and goes against the Scheme mantra "Programming
> languages should be designed not by piling feature on top of feature,
> but by removing the weaknesses and restrictions...".

Please note the discussion of error situations that don't use the term
"signaled" in 1.3.2 (emphasis added):

    If such wording does not appear in the discussion of an error,
    then implementations are not required to detect or report the
    error, though they are encouraged to do so.  /Alternatively,
    implementations may provide non-portable extensions./  Such
    a situation is sometimes, but not always, referred to with the
    phrase ``an error.''  For example, it is an error for a procedure
    to be passed an argument of a type that the procedure is not
    explicitly specified to handle, even though such domain errors
    are seldom mentioned in this report.  Implementations may extend
    a procedure's domain of definition to include such arguments.

--
Why are well-meaning Westerners so concerned that   John Cowan
the opening of a Colonel Sanders in Beijing means   cowan@ccil.org
the end of Chinese culture? [...]  We have had      http://www.ccil.org/~cowan
Chinese restaurants in America for over a century,
and it hasn't made us Chinese.  On the contrary,
we obliged the Chinese to invent chop suey.            --Marshall Sahlins

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