[R6RS] issues in document/lex.tex

Michael Sperber sperber at informatik.uni-tuebingen.de
Sun Aug 27 03:49:25 EDT 2006

William D Clinger <will at ccs.neu.edu> writes:

> 1.  The extensive use of "S-expression" instead of
> "external representation" seems like a step backwards.
> The R4RS and R5RS never use "S-expression", and this
> reflects a deliberate decision to rid ourselves of the
> historical connotations of that term.

I'm not tied to the word "S-expression"---what was important to me was
to distinguish between the <datum> and the value that it represents.
The R5RS doesn't make that distinction.  I preferred "S-expression" as
"external representation" makes an implicit reference to the object
represented by the piece of syntax.  (And it's harder to recognize as
an actual term.)  Maybe "form" would be acceptable?

> 2.  The current draft of lex.tex says "The _nan.0 and
> -nan.0 literals represent the NaN that is the result
> of (/ 0.0 0.0) and may represent other NaNs as well."
> I am pretty sure that the editors never agreed to make
> -nan.0 represent the same NaN as +nan.0.

Ooops, it seems wrote this, but I sure didn't do it consciously.
Sorry about that.

> This change runs counter to the more obvious use of -nan.0 to
> represent NaNs whose sign bit is 1 instead of 0.  Note also that
> that interpretation of -nan.0 was requested by at least one person
> during the discussion of SRFI 77.

Do we leave -nan.0 unspecified then or do we specify it to be the
reslt of (/ -0.0 0.0) ?

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla

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