Is it possible to check the syntax of S-expressions in Emacs? - emacs

I wrote a file of S-expressions. I would like to check if there is some syntax error (i.e. some obvious mismatching between parentheses). Emacs has S-mode, but I don't know if Emacs can check that? Thanks.

Related

How to highlight my own syntax in Emacs?

I am developing my own Domain Specific Language (DSL) and the filename extension is .xyz.
Emacs doesn't know how to highlight syntax in .xyz files so I uausally turn on typescript-mode or json-mode. But the available syntax highlight mode is not good enough for me, so I am considering writing my own syntax highligher for Emacs editor. Any tips on this task? Any toolkit recommendation?
Alternatively, I would be happy with any available mode that highlights common keywords such as class, string, list, variables before =sign and after # sign, braces {}, brackets [], question mark ? and exclamation mark !. Any existing languages have similar syntax?
I am not color-blind and not picky on colors. Any syntax highligher that highlights above syntax can solve my problem.
If you are satisfied with simple syntax highlighting for keywords and comments only, there is a helper for this called define-generic-mode, which is documented in the elisp manual.
Some examples of using it can be found in generic-x.el distributed with Emacs.
But highlighting of variable names is not covered by this. For that, you need to be able to parse the DSL using semantic/bovine, as whether a particular string is interpreted as a variable name depends on context, and not just simple regexp matching.

Best way to customize auto-formatting/auto-indenting in vim for Common Lisp

I would like to know the best way to customize auto-formatting/auto-indenting in vim for Common Lisp.
Auto-formatting (I usually do this by typing '==' in command mode per line) works very well for the base lisp language in vim (e.g., defmacro, defun, lambda, if, with-output-to-string), but any time that new language constructs are defined (e.g., using macros), I find that the formatting for the new construct is often not what I'd like it to be.
For example, here's how vim formats 'when (standard lisp construct) and 'awhen (commonly-used anaphoric version of 'when; not part of lisp standard)
(when 'this
(process 'this))
(awhen 'this
(process it))
I would like 'awhen to auto-format like 'when. Any ideas how I can do this?
Edit: Thanks Gilligan and Tamas for the Slimv recommendation. As a test, I downloaded MacVim (will need this working with terminal vim, but that's a different problem) and slimv, rsynched the slimv download into ~/.vim, launched MacVim, and loaded a .lisp file.
I then started up the lisp server (done through a GUI with MacVim), which loaded up my default lisp executable and core file.
And* since my core file is already loaded with the language extensions that I commonly use (awhen being one of them), awhen formatted correctly right out of the box.
I really like this solution. Instead of [1] having to learn how to tell vim to indent particular functions properly, and [2] writing the code that does this explicitly for each language extension that I define, and [3] updating that code every time I add a new language construct. Instead I leverage slimv to do the formatting for me. And slimv can 'learn' new language extensions, as long as those macros are already loaded into the lisp core that the server session is using. Pretty slick!
I have found that this works well for a particular class of language extensions. Usually ones defined as a macro, using the &body keyword. This seems to 'do the right thing' most of the time, but there are macros I use that still don't properly auto-format. Although I'd say that this is more likely to be an issue with how the macro is written (non-standard language extension) than anything else.
So, this solution works well for me for most cases, and I didn't have to code (and maintain) anything. Great stuff!
This might not be a direct answer to your question but I strongly suggest that you install
the slimv plugin: http://www.vim.org/scripts/script.php?script_id=2531
Its a great plugin which integrates SLIME functionality into vim and besides many other things it also comes with an improved indentation for clisp&clojure. It won't indent awhen the way you want though.
For those who are looking for this topic and don't want to run Slimv, because they aren't working with Common Lisp or other reasons, here is the scoop.
Vim's Lisp indentation is not like that for other languages; it has a special "Lisp mode". This mode is turned on by
:set lisp
which is done automatically for .lisp files. Lisp mode isn't a Vim invention; classic Vi implementations have a Lisp mode turned on with :set lisp. (It's not described by POSIX, unfortunately).
Vim's Lisp mode has a simple mechanism for recognizing forms that require operator-style indentation: namely, there is a parameter called lispwords which holds a comma-separated list of identifiers.
You can prove to yourself that this is the identifier list which is used, even when you're editing a Common Lisp .lisp file with syntax highlighting and all. Simply do :set listwords[TAB] and edit the list to remove something from it, such as defun. Then try to reindent a defun: you will see the function-style indentation now instead of the operator-style.
The syntax highlighting support for Common Lisp is separate from Lisp mode's lispwords parameter; it has its own list of identifiers. For example, in Vim 7.3 if you enter this:
(symbol-macrolet ((foo bar))
you get indented out to here!)
This is in spite of the fact that symbol-macrolet is recognized and colored. Why? It's because symbol-macrolet does not appear in the rather scanty lispwords list, whereas it does appear in the lisp.vim syntax highlighting definition file.
The upshot is that you can cob together some script which scans your directory of .lisp files for macros and generates a set lispwords=... command that is placed into a directory .vimrc.
Or if you are working on a custom Lisp dialect, you can just make its Vim syntax highlighting file customize lispwords when it loads.
Here is an implementation oversight: the lispwords option has no local value; you cannot use setlocal lispwords ... to give it a buffer-specific value. In other words, it appears that (at least in the Vim 7.3 I'm using under Ubuntu) you can't have two or more buffers open holding different dialects of Lisp with different identifiers for indentation. The default contents of lispwords contains a smattering of Lisp and Scheme symbols to try to be a kind of "one size almost fits all" solution.
If you filetype is 'lisp' then I think you need to add indenting rules for your special case in the 'lisp.vim' file in the '/vim7x/indent' directory. You can find a bit more info in help at :h indent-expr and :h indentexpr.
Someone may be able to tell you better, but I believe the default lisp.vim indent file basically does nothing because the built-in function lispindent() is used to get indent values. You will want to:
(1) set function used to get indent values (i.e., indentexpr) to a function in your own indent/lisp.vim file, e.g., GetLispIndent().
(2) in your your GetLispIndent() function you will use lispindent() to get indent values to return for all lines except your special case. See other languages' indent files and read the docs to get an idea for how indentexpr works, e.g, java.vim.
#Kaz's answer is completely correct, but they don't go all the way to answering the original question. Vim's lispwords config string is a comma-delimited list of words; when any of the words in lispwords is found at the beginning of an S-expression, Vim will change the way that S-expression is indented. In other words, it defines the "standard lisp constructs" to which the OP refers. If you view your current lispwords config with :set lispwords, you'll see "when" is included, but "awhen" is not, resulting in the following indentation:
(when 'this
(process 'this))
(awhen 'this
(process it))
To fix this, simply add "awhen" to the config string somewhere in your config, like so:
set lispwords+=awhen,
The trailing comma isn't strictly necessary, but the default value includes it, and is probably wise in case you or a plugin modifier elsewhere. That would turn the original formatting into this:
(when 'this
(process 'this))
(awhen 'this
(process it))
(Tested on my current installation of Vim 9.0)
Note that, as #Kaz points out, this config string is universal, so if you have different dialects of lisp their indentation will all be controlled by this setting. Vim is pretty good about auto-detecting lisps, but you may need so :set lisp if it doesn't recognize your filetype or dialect.

How fix emacs error "old-style backquotes detected"

Any tips on fixing the emacs error "old-style backquotes detected"?
I'm sure the error is coming from some ancient lisp code I wrote.
Thanks.
Are you using the old code with an old or a recent Emacs version (or both)? If you do not need the old backquotes-style code then just replace it with the current style. The Elisp manual tells you how to use backquote.
In general, in the old style:
You needed an extra pair of parens surrounding the whole sexp.
Each construct, such as ,... and ,#... was handled like a function: (,...) and (,#...).
Example with new syntax:
`(foo ,bar ,#toto)
Example with old syntax:
(` (foo (, bar) (,# toto)))

Contextual help in Emacs?

I am not a very good at using Emacs, but the feature I would like the most would be some integration with help/documentation for a particular language/API I use at the moment. I would imagine that there would be help displayed in another buffer depending on where I put my cursor while editing.
I wonder if there is a package that does that, even if it would be very simple, just displaying some file based on the keyword. I think there is, but I cannot find it ("help" is a too generic word).
(In particular, I would like to have this help for Common Lisp, but other languages, such as Java or C, could be useful.)
ILISP and SLIME provide several methods for looking up a function; see the Emacs wiki and the SLIME documentation. Or just built into Emacs itself, there are functions like C-h f to get function help or M-x man; both use the text at the point by default. You could pretty easily adapt them to work for another language of your choice.
Assuming you are using SLIME for common-lisp, you can take a look at slime-autodoc-mode.
Sorry, can't help with a generic solution for this.
You can set up the CLHS root for SLIME in your .emacs file:
(setq common-lisp-hyperspec-root "/usr/share/doc/hyperspec/HyperSpec/")
Adjust the path to where you put your HyperSpec.
Then, C-c C-d h with point at a symbol will look it up there in your browser.
One thing you might like to enable is eldoc-mode, by adding (turn-on-eldoc-mode) to your mode hook functions for the appropriate programming modes.
In ElDoc mode, the echo area displays information about a
function or variable in the text where point is. If point is
on a documented variable, it displays the first line of that
variable's doc string. Otherwise it displays the argument list
of the function called in the expression point is on.
This is probably less than you were after, but it still makes a good companion to a fuller-featured contextual help system, and there are a number of programming modes that support it.

ispell in Emacs LaTeX mode

When I run Emacs command ispell-buffer on an Emacs buffer which is in the LaTeX mode, ispell checks spelling also inside math expressions.
I'd very much like to disable this. Is there an easy way to do it?
I've read about detex but detex does not seem to be integrated into Emacs.
It shouldn't do this, if you are using latexisms (eg. \[ ... \], equation environments, &c) to invoke math mode. Check the contents of ispell-tex-skip-alists; cf. section 6 of the ispell FAQ for what kind of thing should be there.
You can use $..$, $$..$$ to mark out maths using ispell-tex-skip-alists, but beware getting them out of kilter...
Postscript
Check also the value of the ispell-parser variable: this should be 'tex, otherwise ispell will not look for $...$ and $$...$$ regions.
Yes, you can: install aspell instead of ispell, and use flyspell with it.
This doesn't answer your question directly, but I have found Flyspell, an on-the-fly spell checker, incredibly useful when editing LaTeX documents. It still spellchecks inside equations, but it is much easier to ignore a few extra red underlines than ispell's interactive commands.
You may know this, but you can press A during spell checking to add a word to the buffer-local dictionary (that's capital A, lowercase a adds it to the global dictionary). It's not ideal, but this is how I usually suppress spell-checking of technical terms and variable names, etc., in my LaTeX documents.
This AUCTeX mailing list thread : "spell checker (ispell-buffer) complains about products in math modes" has some workarounds and the answer demonstrates how to use ispell-tex-skip-alists.
Another approach is to use ispell-skip-region-alist. The following example is to exclude org-mode src blocks:
(add-to-list 'ispell-skip-region-alist '("#\\+begin_src". "#\\+end_src"))