Re: [Scheme-reports] Padding/placeholders (hashes) in numerical syntax

[John Cowan <cowan@x>]

Ray Dillinger scripsit:

> Also, the R5RS standard requires the result of operations on inexact
> numbers to default to the "highest precision available" on the machine,
> thus any operation on, eg, Short floats that fails to result in a Long
> float is technically in violation of the standard.

That's not how I read 6.2.3.  The text says:

	If, however, an exact number is operated upon so as to produce an
	inexact result (as by `sqrt'), and if the result is represented
	as a flonum, then the most precise flonum format available must
	be used; but if the result is represented in some other way then
	the representation must have at least as much precision as the
	most precise flonum format available.

So it's only operations that produce inexact results from exact
arguments that are required to use the most precise format available.
If the arguments are inexact, there is no such requirement: the result
can have any appropriate precision.

> I'm in agreement that these radix markers could be deleted from the
> standard.  They are after all, widely non-supported.

I agree too, but this view did not command a majority in the WG, so the
precision markers remain part of the standard by default.

> But more importantly, If a distinction between float precision types is
> to be permitted by the standard, then the verbiage about returning
> results of the "highest precision available" ought to be replaced with
> verbiage specifying that inexact results must have at least the same
> precision as the least-precise argument to the operation that produces
> them.

Given the clarification above, and the fact that most implementations
have only one precision, I don't see the need to standardize this.

-- 
Where the wombat has walked,            John Cowan <cowan@x>
it will inevitably walk again.          http://www.ccil.org/~cowan
   (even through brick walls!)

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