Re: [CZT-Users] Z Standard issues related to user-defined operators

[Pablo R. M. <rod...@gm...>]

Thanks for your answer, Petra! It was pretty useful.

Cheers,

Pablo

On Thu, Jun 10, 2010 at 6:46 AM, Petra Malik <Pet...@ec...>wrote:

> Hi Pablo,
>
> You wrote:
> > I am having troubles in determining, from the Z Standard, which names
> > are valid (and which are not) for user-defined operators. In Page 28,
> > the Z Standard assures "Each operator template creates additional
> > keyword-like associations between WORDs and operator tokens.". However,
> > not all WORD seems to be accepted. And I could not find more
> > restrictions about this issue in the Z Standard.
>
> There are a few more restrictions on user-defined operators on page 35
> (8.3 User-defined operators).  Also relevant to your question is page 25
> (7.2 Formal definition of context-free lexis) and page 26 (7.3
> Additional lexical restrictions, notes and examples) as well as page 84
> (Annex A; A.2 LaTeX mark-up).
>
> > the following are rejected:
>
> > \_ <1 \_: X \rel X
>
> "<1" is lexed as two tokens: the DECORWORD "<" followed by DECORWORD
> "1".  If you have a look at page 25, you'll find that "1" is an ALPHASTR
> while "<" is a SYMBOLSTR and if you want to form a word out of those you
> have to put WORDGLUE between the two like in "<_1".
>
>
> > \_ <? \_: \nat \rel \nat \\
>
> "<?" is actually a DECORWORD but since you are using LaTeX mark-up and
> spaces are added around "<" (see page 84 of the Standard) it is lexed as
> two words.  To avoid having spaces added when translating from LaTeX to
> Unicode add braces: "{<}?"
>
> >  \function 40 \leftassoc (\_ ope \_)
>
> Here you need hard spaces: "\_~ope~\_" or even better use the \varg
> latex command "\varg ope \varg" to avoid having the lexer merge the
> underscore and "ope" to a word.  (Note that "_" is defined as WORDGLUE
> on page 21 and then used to glue words on page 25.)
>
> > I suppose that the name cannot start with a letter
>
> It can start with a letter as in the ope example above.
>
> > nor finish with a stroke (case in which it is
> > a DECORDWORD instead of a WORD).
>
> And it can have decorations, too.
>
> > However, I understand that <1 and 1< are valid WORD's.
>
> But they are not; see example above.
>
> > Additionally, which situations, where an operator appear, needs to
> > previously define the corresponding operator template paragraph and
> > which not? The following two paragraphs are accepted without one of
> > these paragraphs:
> >
> > \begin{gendef}[X]
> > \_ <_1 \_: X \rel X
> > \end{gendef}
>
> That's because in one of the toolkits there is an operator template for
> "<" and the mapping to operator tokens is based on the WORD part (see
> page 27).
>
> Hope this helps,
> Petra
>
>
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