Re: Failed to skip from chapter tex file to master pdf file.

[Hongyi Zhao]

On Mon, Jul 12, 2021 at 7:15 PM David Kastrup <dak@gnu.org> wrote:
>
> Hongyi Zhao <hongyi.zhao@gmail.com> writes:
>
> > On Mon, Jul 12, 2021 at 6:31 PM Tassilo Horn <tsdh@gnu.org> wrote:
> >>
> >> Hongyi Zhao <hongyi.zhao@gmail.com> writes:
> >>
> >> >> (delq nil '(nil 1 nil)) ;=> (1)
> >> >> (delq nil '(nil nil nil)) ;=> nil, aka, the empty list ()
> >> >> (eq nil '()) ;=> t
> >> >
> >> > Got it. The `nil' shown in my example just means the empty result list
> >> > (). The `nil' in itself can be used in different context, when it's
> >> > used as boolean variable, it means false. But it can also be used to
> >> > represent an empty list ().
> >>
> >> Exactly that. :-)
> >
> > Perhaps this is one of the reasons why LISP is efficient, powerful,
> > abstract and highly concise. Another distinguishing feature is that it
> > only relies on symbol expression to do all complicated logical without
> > using syntax, just as many other languages do. I find myself becoming
> > more and more fond of this language, because I don't need to memorize
> > the tedious grammar rules and just think about what I want to do.
>
> Well, the absence of "tedious grammar rules" is due to LISP not actually
> having an input language utilising humans' ability to visually peruse
> linguistic and graphic conglomerates.  Instead you directly enter a
> program's parse tree in a data representation specifically optimised for
> list entry.
>
> That makes it rather straightforward to use LISP itself for generating
> and analysing programs.  It also means that LISP programs without a good
> indentation strategy are inordinately harder to read for humans than
> unformatted input in other languages.

The point is, to a human, it is unformatted, to a computer, it looks
formatted, and vice versa. So, what we see here is a very ironic
thing: a grammar absent language is used to help develop, analysis,
and debug other languages which have various grammar rules.

On the other hand, all Turing complete languages are equivalent, so at
least in theory, each of them can do anything's done by others of
them.

> As sort of a counterthesis, an indentation-sensitive language like
> Python makes it in contrast quite hard to write (and parse) programs
> correctly from within code.

Hongyi
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province