Re: [Scheme-reports] "It is an error" is misleading

[John Cowan <cowan@x>]

Noah Lavine scripsit:

> This may be obvious to you, but the objection here is that the phrase "is
> an error" is confusing in R7RS-small because it also has an error
> procedure. This confusion did not exist in R5RS and previous standards. Of
> course if someone is confused, the WG can always point the difference out -
> but I think that the goal in writing a standard is to be so clear that you
> don't need to answer questions like this. So if there is a phrase that is a
> potential source of confusion for experienced Schemers, then it would be
> best to change that phrase, even though that change has no effect on the
> meaning of the standard.

Rather than changing the phrase, which is pervasive, I have made two
changes:

1) I have clarified that `error-object?` does not necessarily answer #t
to objects raised when signaling an error.

2) I have rewritten the "is an error" section to read thus:

    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.  Such a situation
    is sometimes, but not always, referred to with the phrase
    ``an error.''  In such a situation, an implementation may
    or may not signal an error; if it does signal an error, the
    object that is signaled may or may not satisfy the predicates
    {\cf error-object?}, {\cf file-error?}, or {\cf read-error?}.
    Alternatively, implementations may provide non-portable
    extensions.

    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 signal an error, extend
    a procedure's domain of definition to include such arguments,
    or fail catastrophically.

> The WG has worked very hard, and I appreciate it. I hope it will take these
> comments as constructive criticism, meant only to make R7RS-small even
> better.

We are attempting to do so.

-- 
John Cowan    http://ccil.org/~cowan    cowan@x
SAXParserFactory [is] a hideous, evil monstrosity of a class that should
be hung, shot, beheaded, drawn and quartered, burned at the stake,
buried in unconsecrated ground, dug up, cremated, and the ashes tossed
in the Tiber while the complete cast of Wicked sings "Ding dong, the
witch is dead."  --Elliotte Rusty Harold on xml-dev

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