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Re: Conditional definition of Scheme functions and typesetting of trees


Chronological Thread 
  • From: Massimiliano Gubinelli <address@hidden>
  • To: Giovanni Piredda <address@hidden>
  • Cc: address@hidden
  • Subject: Re: Conditional definition of Scheme functions and typesetting of trees
  • Date: Wed, 18 Nov 2020 00:57:50 +0100
Dear Giovanni,

independently of the way you achieve this, I do not understand what it is
useful for in your application. Why you want to change the appearence of the
* according to whether you are in an equation or not? Cannot you simply say
that all the unit of measure are in math mode? For example, usually when I
type numbers which have a matematical meaning I always initiate an equation.

Max


> On 18. Nov 2020, at 00:37, Giovanni Piredda <address@hidden> wrote:
>
> Hi Max,
>
> I think I understand it now (I will try it tomorrow). Thanks for the
> explanation.
>
> I have a memory of seeing a procedure that finds out if a tree is inside a
> math environment, and that I have even tested it, but I need to find it
> again.
>
> Perhaps that is the way to achieve what I would like to achieve
> (typesetting something in a way that depends on where it is, and not in a
> way that depends on where *the cursor* is), but I first need to find it
> again in the documentation).
>
> G.
>
>
> On 18.11.20 00:32, Massimiliano Gubinelli wrote:
>> As an example, try to use my macro and then create an equation and enter
>> it with the cursor, then make "Update all" (Shift+Cmr+R) and you will see
>> that the value of all the instances of the macro will change to "+++". If
>> now you go with the cursor on the text and then you do again "Update all",
>> then all the instances change to "xxxx". This depends where the cursor is,
>> not where the macro are called. And "Update all" just force TeXmacs to
>> rexpand all the document from the start.
>>
>> Best
>> Max
>>
>>
>>> On 18. Nov 2020, at 00:29, Massimiliano Gubinelli <address@hidden> wrote:
>>>
>>> Dear Giovanni,
>>> my understanding of the matter can be wrong (or not totally correct)
>>> however is as follows:
>>>
>>> 1) In order to display your document, TeXmacs need to transform the
>>> document tree into a series of boxes which indicate where and what put on
>>> the screen or on the paper. This transformation go thru several phases,
>>> one of which is the macro expansion phase, i.e. markup in the document is
>>> evaluated until primitive markup is reached, which then allows to compute
>>> boxes and the material which will eventually end up on your screen.
>>>
>>> 2) Every time the document is modified, for example by the user editing
>>> it inserting some text in some position of the document tree, TeXmacs
>>> perform the computations in 1) to transform the modified document tree
>>> into a new sequence of rendering instructions.
>>>
>>> 3) If you put some \extern markup in the document, then when TeXmacs
>>> tries to expand that markup it (by definition) goes on by calling the
>>> scheme procedure and replacing the \extern markup with the result of the
>>> scheme procedure. Now, the scheme procedure does not have *any*
>>> informations on where the \extern markup was in the document tree. So
>>> scheme cannot know if we were in an equation or in a piece of text.
>>>
>>> Your confusion is to believe that in-math? returns true in a situation
>>> where you use \extern inside an equation. This is not true, in my
>>> understanding.
>>>
>>> in-math? is true only if the *editor* is in math mode, that is your
>>> cursor is inside an equation. This is a global mode of the editor and if
>>> it happens that your macro is evaluated again at that moment, then the
>>> predicate returns true, but this does not depend on the position of your
>>> \extern in the document tree, but on the current position of the cursor
>>> at the moment TeXmacs tries to recompute that part of the tree.
>>>
>>> Maybe this description is not totally correct (I'm not sure how and when
>>> exaclty TeXmacs goes to a reexpansion of the macros) but seems coherent
>>> with the bizzare behaviour of your macros.
>>>
>>> Also try \extern with a procedure of the form
>>>
>>> (define (myfunc) (if (in-math?) "+++" "xxxx")))
>>> to see how, even when you put it in regular text, you can have "+++" if,
>>> right away you then enter into math mode.
>>>
>>> HTH,
>>> Max
>>>
>>>
>>>
>>>> On 17. Nov 2020, at 23:29, Giovanni Piredda <address@hidden> wrote:
>>>>
>>>> I am going to answer your previous message (thanks for that by the way)
>>>> but before that: I do not follow the explanation in this message on the
>>>> in-math? predicate, I have an idea of what you might mean, but maybe the
>>>> idea is wrong :-)
>>>>
>>>> Let me write it down here.
>>>>
>>>> Starting from:
>>>>
>>>> "As I open the file, where I have the macro (which calls Scheme code via
>>>> extern) both inside math and outside math, they are all executed as if
>>>> in text mode.
>>>>
>>>> If I edit one of them, now the predicate in-math? has effect."
>>>>
>>>> you say that when I open the file TeXmacs is only typesetting (and
>>>> therefore uses the default function, as (in math?) returns always #f),
>>>> but when I am editing TeXmacs knows what I am editing and lets Scheme
>>>> know. Is it that?
>>>>
>>>> The follow-up question in this case is how can I obtain what I want,
>>>> that is a different function being called ever time the macro is
>>>> executed, that is also at the opening of the file. The aim seems
>>>> sensible to me - typesetting something in one way when in math and in
>>>> one way when in text (as I said above, now it is working when I
>>>> write/edit, it is not working if I close and open again a document).
>>>>
>>>> Besides, doing Document->Update all hangs the document for a one/two
>>>> minutes (Ubuntu 20.10, I observed it in another document too), makes the
>>>> macros work well (upright in math, no asterisks, so it is recognizing
>>>> the math), which is pretty surprising, but destroys the page setup
>>>> (margins are lost).
>>>>
>>>> G.
>>>>
>>>>
>>>> On 17.11.20 22:50, Massimiliano Gubinelli wrote:
>>>>> Going back to your attempt: I think that the predicate in-math? cannot
>>>>> be used to check whether the typesetter is working on an equation or
>>>>> not. No information is passed to Scheme about the internal status of
>>>>> the typesetter when you call a \extern markup. You can pass
>>>>> informations only via parameters. So your unitSpacer has no way to know
>>>>> if the evaluation is inside some math markup or not.
>>>>>
>>>>> The predicates in-math?, etc.. are just to check if the editor is in
>>>>> text, prog, or math mode, for example. Thats is completely separate on
>>>>> the status of the typesetter.
>>>>>
>>>>> HTH,
>>>>>
>>>>> Max
>>>>>
>>>>>
>>>>>
>>>>>> On 17. Nov 2020, at 19:25, Giovanni Piredda <address@hidden> wrote:
>>>>>>
>>>>>> I post this here because I think that while being about Scheme in
>>>>>> TeXmacs is still of general interest. I have found a way of
>>>>>> circumventing both issues (which may be ok, in case I will ask about
>>>>>> this in another post) but I am curious to know the reason of the
>>>>>> behaviours I observe.
>>>>>>
>>>>>> First issue.
>>>>>>
>>>>>> I have defined a Scheme function with the following:
>>>>>>
>>>>>> (tm-define (unitSpacer) ; default, will be used in regular text
>>>>>> `(hspace "0.5spc"))
>>>>>> (tm-define (unitSpacer)
>>>>>> (:require (in-math?))
>>>>>> "*")
>>>>>>
>>>>>> As far as I understand, the first definition is the default and it is
>>>>>> overridden by the second when I am in math.
>>>>>>
>>>>>> In my tests, this happens only in open documents. At the first opening
>>>>>> of a document, only the first definition is used. Does anyone have a
>>>>>> hint on what is happening? Developers ;-) ?
>>>>>>
>>>>>> ===
>>>>>>
>>>>>> Second issue.
>>>>>>
>>>>>> In math mode, the program I wrote outputs groups of letters, each
>>>>>> wrapped in a <with|math-font-shape|right primitive, and interleaved
>>>>>> with the character "*".
>>>>>>
>>>>>> Example of output, copied from the terminal using (display ...)
>>>>>>
>>>>>> <tree 2 <with|math-font-shape|right|kg>*<with|math-font-shape|right|m>>
>>>>>>
>>>>>> I call this from a TeXmacs macro in math mode and I get a typeset
>>>>>> output where the asterisk appears as such (while I would like it to be
>>>>>> interpreted as an implicit multiplication)
>>>>>>
>>>>>> If I copy the output from the terminal, strip the outermost <tree
>>>>>> primitive and place it inside a math primitive (opening the .tm file
>>>>>> with a text editor) the asterisks do not appear (as I thought they
>>>>>> shouldn't).
>>>>>>
>>>>>> Again, suggestions?
>>>>>>
>>>>>>


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