Different indent styles of Ocaml in Emacs - emacs

I am writing Ocaml code under Emacs. Currently, the indent style is like the following, that is, the code where a variable is defined by let is a little bit on the left of let.
let v = 5 in
Printf.printf "v= %d\n" v
I also see some files written by others, when I open them, the indent style is that the code is in the same column as let:
let v = 5 in
Printf.printf "v= %d\n" v
I think the second style looks better, does anyone know where I could setup Emacs so that my Emacs takes the second style?
Thank you very much!

You can also use ocp-indent which indents by default using the second style.

look to the 'tuareg-in-indent' setting, that sets how much ident should be done (0 to disable) - you can customize it with M-x customize-variable...
P.S. you can also look to 'tuareg-let-always-indent' variable...

Related

LaTeX math mode ($...$) font color in org mode

I have just started using org-mode and it looks awesome. The only issue that I have so far is that when I write a text in mathmode ($...$) it appears in the standard-text font color.
So, I would like to make org-mode to identify the mathmode text and be able to present it in some other color. Note that I don't need to change the color of the actual equation, just the source text in org-mode.
Here is an example of how the text is currently presented
A paper by Rohnert, titled "Moving a disc between polygons" introduces
a structure using which one can generate a solution (path) for
a given query in $O(\log n) + k$ time.
and how I would like it to look
A paper by Rohnert, titled "Moving a disc between polygons" introduces
a structure using which one can generate a solution (path) for
a given query in $O(\log n) + k$ time.
(Note that I would prefer to display in some given color, e.g. red, and not bold face.)
In Emacs version 24.4 and later, this is controlled via the variable org-highlight-latex-and-related:
Non-nil means highlight LaTeX related syntax in the buffer. When non
nil, the value should be a list containing any of the following
symbols:
`latex' Highlight LaTeX snippets and environments.
`script' Highlight subscript and superscript.
`entities' Highlight entities.
So something like
(eval-after-load 'org
'(setf org-highlight-latex-and-related '(latex)))
in your init should help. Such code is formatted according to the face org-latex-and-related.
In earlier versions, the variable org-highlight-latex-fragments-and-specials, which is a simpler nil / non-nil variable:
(eval-after-load 'org
'(setf org-highlight-latex-fragments-and-specials t))
In this case, the face org-latex-and-export-specials is used.

how to freely format comments in cc-mode

I'm quite new to cc-mode and I'd like to configure it to allow me to freely format and use tabs in multiline comments. This is important to me because I want to use cog.py in my source file and need to be able to format the python source in the comment correctly. I'd be ok with comments not beeing autoindented at all, however I'd like to keep auto indenting the rest of the source code.
Example:
...
/*
[[[cog
import cog
for x in ['a','b','c']:
>cog.outl(x)
]]]
*/
...
In the line marked with > I'd like to press TAB to indent the line. cc-mode simply does nothing at all if i do so. I could use spaces there (which is inconvenient) but every (semi-)automatic re-indentation of this block would cause the spaces to vanish and therefore the python code to be incorrectly indented (which is what happens if i happen to press tab somewhere on this line after indenting it with spaces).
I tried to start emacs without my .init to be sure this is default behavior and not modified by my configuration so far. I've done google searches and read the documentation of the cc-mode variables / functions I stumbled upon (cc-mode online docs) while searching for a solution (i.e. c-indent-comments-syntactically-p, c-indent-command, c-tab-always-indent,...) but none of these seemed to solve my question.
EDIT1:
Thanks to abo-abo's idea of a "multi-major-mode" setup i've stumbled upon mmm-mode and have set up automatic switching to python mode for a cog section, which fixes most of my problems.
The only remaining problem is reindenting the whole file or a region containing a cog section. Can I somehow tell cc-mode to not change anything in comments while reindenting the file? mmm-mode + that would be a perfect solution for me.
You can use M-i to force a tab indent on the lines that you want, so you can use it to indent your comments.
You can also change your comments to use // instead. Just select your python code snippet, and do M-x comment-region:
// def foo(x):
// print 'hi'
Then the autoindent won't mess up your indentation.

How do I auto-fill lines in brackets in emacs (markdown-mode)?

I'm relatively new to Emacs, but have been experimenting with it to see if it would be worth switching. I write in Markdown and use pandoc to convert to whatever I need. In case it matters, I'm running Emacs 23.3.1 on Ubuntu 12.04.
I'm a graduate student in the humanities, so my writing is heavy on the footnotes. Footnotes, in pandoc, are formatted within square brackets. The problem I'm having is that auto-fill mode seems to ignore text within brackets, so my footnotes end up snaking their way across the page--and the only fix I've been able to find is to manually break the lines myself, every time I edit the paragraph. That's obviously less than ideal. (I could also give up on inline footnotes, and leave them all separate references, but I'd prefer not to, and it doesn't seem like that should be necessary.)
So my question is, is there a way to make auto-fill mode operate on text within brackets, too? Is there a reason it doesn't by default?
Many thanks,
-- Brian
It turns out that markdown-mode, as of v. 1.7, deliberately avoids breaking lines in square brackets in order to avoid breaking links--which is the most common use of brackets for Markdown. See http://jblevins.org/projects/markdown-mode/rev-1-7.
Brian,
Add the following to your init file† to allow auto-fill in markdown-mode to break lines inside square brackets:
(require 'markdown-mode)
(defun markdown-nobreak-p () nil)
What we did is redefine the function "markdown-nobreak-p" (originally defined here: http://jblevins.org/git/markdown-mode.git/commit/?id=66566a55 ) to always return "nil" which means "yes you are allowed to break at this point". The original version of this function would return non-nil for points inside square brackets.
† http://www.gnu.org/software/emacs/manual/html_node/emacs/Find-Init.html
Auto-fill by itself does not prevent filling inside brackets. It can be told to do so by the major-mode, tho, so I guess the problem depends on your major mode. If you're using mardown-mode, then please report this problem to its maintainer. In any case, you may want to try and use M-q to explicitly fill the paragraph, since it does not always follow the same conventions as auto-filling: it's more explicit than auto-fill, but still more automatic than placing the newlines by hand.

Problem writing a snippet containing Emacs Lisp code

I've been trying to make use of a cool feature of YASnippet: write snippets containing embedded Emacs Lisp code. There is a snippet for rst-mode that surrounds the entered text with "=" that is as long as the text such as in
====
Text
====
Based on this snippet, I decided to slightly modify it (with Elisp) so that it comments out these three lines depending on the major mode you are in (I thought that such a snippet would be useful to organize the source code). So I wrote this:
${1:`(insert comment-start)`} ${2:$(make-string (string-width text) ?\-)}
$1 ${2:Text}
$1 ${2:$(make-string (string-width text) ?\-)}
$0
This code works relatively well except for one problem: the indentation of these three lines gets mixed up, depending on the major mode I'm in (e.g., in emacs-lisp-mode, the second and the third lines move more to the right than the first line).
I think the source of the problem might have something to do with what comes after the string ${1: on the first line. If I add a character, I have no problem (i.e., all three lines are correctly aligned at the end of the snippet expansion). If I add a single space after this string, the misalignment problem still continues though.
So my question is: do you know of any way of rewriting this snippet so that this misalignment does not arise? Do you know what's the source of this behaviour?
Cheers,
From Writing snippets:
yas/indent-line
The variable yas/indent-line controls the indenting. It is bound to 'auto by default, which causes your snippet to be indented according to the mode of the buffer it was inserted in.
Another variable yas/also-auto-indent-first-line, when non-nil does exactly that :-).
To use the hard-coded indentation in your snippet template, set this variable to fixed.
To control indentation on a per-snippet basis, see also the directive # expand-env: in Writing Snippets.
For backward compatibility with earlier versions of YASnippet, you can also place a $> in your snippet, an (indent-according-to-mode) will be executed there to indent the line. This only takes effect when yas/indent-line is set to something other than 'auto.
for (${int i = 0}; ${i < 10}; ${++i})
{$>
$0$>
}$>

How to enforce maximum line length in Emacs?

In Emacs, how can I enforce a maximum line length of, say, 80 characters? I want it to insert proper line breaks in my code, much like fill-paragraph for text, if possible, with the correct insertion of the second part of the line.
Here a little example:
LongNameType<PrettyLong, AlsoLong> doSomethingWithLongFunctionName(int a, int b);
foo();
If I actually do fill-paragraph it becomes:
LongNameType<PrettyLong, AlsoLong>
doSomethingWithLongFunctionName(int a, int b); foo();
whereas I'd prefer this:
LongNameType<PrettyLong, AlsoLong>
doSomethingWithLongFunctionName(int a, int b);
foo();
There are a number of packages which warn you of line length limits. Personally, I use wide-column, which changes the cursor color depending on its current column.
fill-paragraph and auto-fill-mode deliberately don't wrap code. There are just too many ways to do it and it'd probably get it wrong. They will wrap comments, but that doesn't help you here.
The only way I've ever done it to to explicitly put the where I want the text to break. Then the auto-indent should put the broken line in the right place.
Are you trying to reflow a large body of existing code? Or trying to have auto-fill work on code you are writing now?
Not really an emacser, but what happens if you turn on auto-fill-mode while in c++-mode?
C++ mode should give you auto-indent, and auto-fill-mode gives you line-wrapping....
I use modeline-posn package. It highlights column number in the modeline if it's greater than specified value.
You should check out one of the many "vertical line" libraries for Emacs. Some keep a vertical highlight line over the entire buffer at point at all times (not really what you want) but other libraries put the vertical highlight on a fix column at all times, which is not really what you want, but you can immediately see when you ought to be wrapping lines.
Try
'(c-max-one-liner-length 80)
'(fill-column 80)
'(c-ignore-auto-fill (quote (string cpp)))
Hope it helps.
You could use the more advanced clang-format package.
You have to install clang-fromat along with it's emacs package.
Add this to your .emacs (setq clang-format-style "file") or add to custom-set-variables '(clang-format-style "file").
Generate your template style by clang-format -style=gnu -dump-config > .clang-format then place into your project's root.
Customize .clang-format as you like and change ColumnLimit: 120 to 80 or whatever value you want.
That would force column limit using clang-format tool.
Reference:
ClangFormatStyleOptions.
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