Re: Are pragmas always "instructions"? (was: Re: What is a pragma?)

> But looking again at your note, I'm not sure you did tell me that you
> you do not mean to suggest the pragmas always have imperative semantics
> but can also have declarative semantics.  It seems to follow from your
> attempt to persuade me that "instructions" can be declarative, but I've
> made wrong inferences before.

You’re not wrong. I entirely agree that pragmas can have either imperative or declarative semantics.

Sent from my iPhone

> On 29 Jan 2022, at 19:20, C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com> wrote:
> 
> 
> Bethan Tovey-Walsh writes:
> 
>>> saying that pragmas convey information (and in particular information
>>> not conveyed by the standard semantics of ixml, or not conveyed in
>>> the same way) seems more general, and is intended to cover both
>>> declarative and imperative semantics (and anything else).
> 
>> For my money, it’s much *too* general. Comments also convey
>> information, for example.
> 
> It would indeed be much too general if offered as a definition; it does
> not allow pragmas to be distinguished from other things that convey
> information.  But it wasn't offered as a definition, and even the
> non-definitional characterization of pragmas from which it was drawn
> mentions other properties as well.  I picked out the word 'instruction'
> and the phrase "convey information" to illustrate what appears at first
> glance to be a striking difference in understanding.
> 
>> Firstly, I wonder whether we can help you make peace with
>> “instructions”? I have two ways of looking at it that may or may not
>> help:
> 
>> a) An instruction needn’t be simply a command. Think of assembly
>> instructions for some furniture: it’s totally reasonable to see items
>> of the type “The square peg goes into the square hole”, or “You should
>> have 12 long bolts and 6 short bolts”. They’re declaratives, not
>> imperatives, but I don’t think that means they’re not properly
>> instructions.
> 
> I agree that declarative statements can be used to convey to someone how
> to do something, but I think that most assembly instructions I have
> experienced have in fact been in the imperative mood.  They did not say
> "The square peg goes into the square hole"; they said "Insert peg A into
> hole Q23".  But I am too lazy to go hunt up the nearest instruction book
> so I can hold it up and say either Aha, triumphantly, or Wow, I didn't
> expect that, with an unconvincing air of being glad to have learned
> something instead of being sheepish at being refuted.
> 
> In computing, I think it will be hard to find usages of the word
> "instruction" as anything but a synonym of "command", with imperative
> semantics.  Documentation for languages with a strictly declarative
> semantics tends to avoid "instruction" I think, in favor of "statement"
> or "expression" or other terms like Prolog's "clause".  Can anyone think
> of exceptions to that claim?
> 
> (Wow.  I didn't expect that: since 1.0, XSLT has referred to most of its
> constructs as "instructions".  I confess my reaction at the moment is
> that that verges on the bizarre, but I seem to have lived with the usage
> for a long time without being bothered by it.)
> 
> Intuition being notoriously unreliable, I checked the dictionaries on my
> shelf (but not the ones in the front room).  "Webster's New World
> Dictionary" (World Publishing, 1968) seems to make the view you suggest
> a bit of a stretch.
> 
>  1. an instructing; education.
>  2. knowledge, information, etc. given or taught; any teaching; lesson.
>  3. pl. directions; orders.
> 
> I take 1 and 2 to refer to the activity of instruction, not to a
> concrete written message of any kind.
> 
> The Random House American College Dictionary (ed. Clarence L. Barnhart,
> 1948) is similar but more detailed.
> 
>  1. act or practice of instructing or teaching; education.
>  2. knowledge or information imparted.
>  3. an item of such knowledge or information.
>  4. (usually pl.) an order or direction.
>  5. act of furnishing with authoritative directions.
> 
> Here items 2 and 3 at least come a step in your direction, though I
> think they are intended to describe abstract things, not pieces of
> writing.
> 
> COBUILD (Collins, 1988), on the other hand, which focuses more or less
> relentlessly on empirical observation of current usage ("helping
> learners with REAL English", it says on the cover), is much less
> sympathetic to a declarative view:
> 
>  1 An instruction is something that someone tells you or orders you do
>  to.  EG I disagree with what I am doing but it is an instruction, so I
>  will carry it out.
>  2 Instruction in a subject or skill is teaching that someone gives you
>  in it.
>  3 Instructions are clear and detailed information on how to do
>  something, especially in written form, EG Read the instructions before
>  you switch on the engine... ... the manufacturers' instruction book.
> 
>> b) Pragmas instruct the processor. They either instruct it “to…” or
>> instruct it “that…”. The former is imperative; the latter,
>> declarative.
> 
>> Secondly, if “instructions” still doesn’t work for you, how about
>> “directives” or “directions”?
> 
> Still feels very imperative, and off-target in roughly the same way as
> "declarations" would be, only in the opposite direction. 
> 
> But since we are not drafting spec prose, I don't think we need to
> persevere until we reach agreement on the word "instruction".
> 
> If you tell me that you do not mean to suggest that pragmas always have
> imperative semantics, but that they can have imperative or declarative
> semantics, then we appear to agree on the semantics of pragmas, at least
> in broad terms, and we each have an interesting factoid about the odd
> lexical semantics other people associate with the word "instruction".
> 
> But looking again at your note, I'm not sure you did tell me that you
> you do not mean to suggest the pragmas always have imperative semantics
> but can also have declarative semantics.  It seems to follow from your
> attempt to persuade me that "instructions" can be declarative, but I've
> made wrong inferences before.
> 
> -- 
> C. M. Sperberg-McQueen
> Black Mesa Technologies LLC
> http://blackmesatech.com

Received on Sunday, 30 January 2022 12:40:55 UTC