Re: Motion P1788/M0029.01: Level-3-interface-only --- Final version to vote on
> From: John Pryce <prycejd1@xxxxxxxxxxxxx>
> Subject: Motion P1788/M0029.01: Level-3-interface-only --- Final version to vote on
> Date: Tue, 13 Dec 2011 19:35:47 +0000
> To: stds-1788 <stds-1788@xxxxxxxxxxxxxxxxx>
>
> P1788
>
> . . .
>
> Regards
>
> John Pryce
>
> Motion 29
> =========
> . . .
>
> Rationale
> =========
> . . .
>
> However they also support an interchange medium at the binary level. One
> can't specify this for a "general" T assuming only what's in the Explicit/
> Implicit motion 19, but for each 754-conforming type we can easily define
> its interchange format (should it be "interchange type"?) as follows:
You are correct that it SHOULD be "interchange type" but please
continue to use the expression "interchange format".
During the 754 deliberations we tried to use the word "type" to
refer to our datatypes but the compiler people in the room always
objected on the grounds that a compiler notion of "type" carries
with it baggage that we could neither discuss nor agree upon.
So you will notice that the word "type" is largely eliminated
from the 754 document.
Indeed, the word "format" was controversial as well. And the
use of it in 754 is not quite the same as the use of it elsewhere.
We use it to refer to an abstraction separate from its bit pattern
for which we reserve the word "representation".
I am not a fan of such tortured prose but it is something that
seems to come out naturally in the committee process.
> - Nonempty xx=[xlo,xhi] is represented by bits(xlo) + bits(xhi).
> | - Empty xx is represented by bits(NaN) + bits(NaN).
> Here bits(x) is the bit-string of an F-number x (as described in the 754
> standard), and + means concatenate.
>
> . . .
>
John,
Will we be seeing a new PDF based on these friendly
amendments or is this it?
Yours,
Dan