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LaTeX auto activating snippets in Emacs

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By Thomas Speckhofer 11 min read

This page contains an overview of my $\LaTeX$ setup in Emacs. It enables one to write LaTeX code in a very convenient and fast way (sufficiently fast to take notes in real time during lectures). This is achieved by using auto-expanding snippets. In order to expand such a snippet, it is not necessary to press an extra key such as tab or enter—instead, it gets triggered immediately after typing a specific key sequence, without interrupting the flow of typing. The setup is inspired by this article by Gilles Castel, where an analogous system for Vim is described. My setup uses the laas and CDLaTeX packages, with some modifications and lots of additional snippets.

LaTeX auto activating snippets in Emacs

Contents:

Overview and usage

As explained above, the main purpose of this setup is that it provides using auto-activating snippets to speed up and simplify typing $\LaTeX$ code. For a detailed expanation on what auto-activating snippets are and why they are useful, I recommend reading the aforementioned article by Gilles Castel. Here are some examples of the most useful snippets which are triggered automatically while typing in this setup when working in a .tex file:

  • km (“math mode”) is replaced by $$, and the cursor is placed inbetween the dollar signs.

  • dm (“display math mode”) is replaced by \begin{equation*} \end{equation*}.

  • <= is replaced by \leq, and >= is replaced by \geq, => is replaced by \implies.

  • Greek letters: .a is replaced by \alpha, .b by \beta, .e by \epsilon, ..e by \varepsilon, .G by \Gamma etc.

  • sin, cos, lim, int, sum etc. are replaced by \sin, \cos, \lim, \int, \sum etc.

  • sr (“squared”) is replaced by ^2, cb by ^3 (“cubed”), td by ^{}, and inv by ^{-1}.

  • oo is replaced by \infty, ... by \dots, ** is replaced by \cdot and xx is replaced by \times.

  • // is replaced by \frac{}{}, the cursor is placed in the first curly brackets pair and you can use the tab key to jump into the second pair and to exit the brackets.

  • xbar is replaced by \bar{x}, and there are analogous snippets for yhat, ztil (“tilde”) etc.

  • lr( is replaced by \Bigl( \Bigr) (and you can use tab to navigate), norm is replaced by \| \| etc, set is replaced by \{ \} etc.

  • NN is replaced by \mathbb{N}, analogously for ZZ, QQ, RR etc.

  • UU is replaced by \cup (union), Nn by \cap (intersection), WW by \wedge, VV by \vee, uuu by \bigcup etc.

  • AA is replaced by \forall, EE is replaced by \exists.

  • Automatic subscripts: x0 is replaced by x_0, a10 by a_{10}, f_ by f_{}. For some letters (such as n), there are snippets like xnn, which is replaced by x_n.

Apart from km and dm, the above snippets are only triggered in math environments. A complete list of all snippets can be found below. As an example, you can now press the following key sequence:

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exp(x) = sum_n=0[tab]tdoo[tab] //xtdn[tab]n!

(where [tab] stands for the tab key), and without pressing any other keys to activate the snippets, this is automatically replaced by the following LaTeX code:

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\exp(x) = \sum_{n=0}^{\infty} \frac{x^n}{n!}

Similarly, you can press the following key sequence:

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AA..e>0EEn0innNNAAn>=n0: normxnn-x[tab]<..e

which results in the following LaTeX code:

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\forall \varepsilon>0\exists n_0\in \mathbb{N}\forall n\ge n_0: \|x_n-x\|<\varepsilon

Clearly, using these snippets has the potential of saving quite some time, and arguably, it is also much more convenient than typing all the backslashes which are needed when typing the code manually, especially on a German keyboard.

In addition to the laas package, my setup uses the CDLaTeX package for some additional autocompletion functionality, and in particular for its tab command: By pressing the tab key, you can, for example, navigate between the curly brackets in \frac{}{} and exit the brackets after typing the denominator. This does not only work immediately after expanding the // snippet (while the snippet is still “active”), but anytime and anywhere in the file, even after writing somewhere else and putting the cursor back in the first pair of parentheses in \frac{}{}, you can press tab to jump into the next pair of parentheses.

Installation

In order to install this setup, proceed as follows:

  1. Install Emacs. I am using Doom Emacs with the “Evil” mode for Vim-like navigation, but the setup should work analogously in other Emacs configurations.

  2. Set up $\LaTeX$ support in Emacs, e.g., by uncommenting the latex entry in your init.el file in Doom Emacs.

  3. Install the CDLaTeX package. In Doom Emacs, this can be done by adding the following to your init.el file (restart Emacs or execute the doom/reload command after installing a new package).
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           (latex             ; writing papers in Emacs has never been so fun
        +cdlatex)

  4. Install the laas package: You can download my modified file laas.el and put it into the directory ~/.emacs.d/lisp/ (create it if it doesn’t exist). This file already contains all my additional snippets, which are listed below. I have also made some other small modifications (such as disabling the built-in fraction snippet, which I am not using)–search the file for EDIT to see my changes.

  5. Add the following code to your Emacs configuration file (e.g., config.el in Doom Emacs). The first lines are important if you want to use jk and kl as your evil-escape-key-sequence. Usually, this would interfere with snippets containing the letter k (due to some small delay), but using the key-chord package fixes this issue. Next, the packages CDLaTeX and aas (“Auto Activating Snippets”) are loaded, and some snippets are added to the aas package. These are triggered at any point in text, not only in math environments. Finally, the file laas.el is loaded, containing those LaTeX snippets which are only triggered in math environments.
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    (require 'key-chord)
(key-chord-mode 1)
(key-chord-define evil-insert-state-map  "jk" 'evil-normal-state)
(key-chord-define evil-visual-state-map "jk" 'evil-normal-state)
(key-chord-define evil-insert-state-map  "kj" 'evil-normal-state)
(key-chord-define evil-visual-state-map "kj" 'evil-normal-state)

(require 'latex)
(require 'cdlatex)

(after! latex
  (define-key LaTeX-mode-map [tab] 'cdlatex-tab))
(add-hook 'LaTeX-mode-hook 'cdlatex-mode)

(after! cdlatex
  (setq cdlatex-math-modify-prefix "f7") ;; Use f7 instead of '
  (define-key LaTeX-mode-map "'" nil)
  (define-key cdlatex-mode-map "'" nil))

(use-package aas
  :hook (LaTeX-mode . aas-activate-for-major-mode)
  :hook (org-mode . aas-activate-for-major-mode)
  :config
  (aas-set-snippets 'text-mode
    ;; expand unconditionally
        "km" (lambda () (interactive)
         (yas-expand-snippet "\$$0\$"))
        "dm" (lambda () (interactive)
         (yas-expand-snippet "\\begin{equation*}\n  $0\n\\end{equation*}"))
         ;; alternative snippet:
         ;; (yas-expand-snippet "\\[\n  $0\n\\]"))
        "alig" (lambda () (interactive)
          (yas-expand-snippet "\\begin{align*}\n  $0\n\\end{align*}"))
        "eqn" (lambda () (interactive)
          (yas-expand-snippet "\\begin{equation}\n  $0\n\\end{equation}"))
        "cite" (lambda () (interactive)
          (yas-expand-snippet "\\cite{$0}"))
        "cref" (lambda () (interactive)
          (yas-expand-snippet "\\Cref{$0}"))
        "eqref" (lambda () (interactive)
          (yas-expand-snippet "~\\eqref{$0}"))
        "latex"  "\\LaTeX"
        "TEMPLATE" (lambda () (interactive)
          (yas-expand-snippet "\\documentclass[12pt,a4paper,oneside]{article}\n\\usepackage[utf8]{inputenc}\n\\usepackage[T1]{fontenc}\n\\usepackage{lmodern}\n\\usepackage[left=2.5cm,right=2.5cm,top=2.5cm,bottom=2.5cm,headsep=1.2cm]{geometry}\n\\usepackage{amsmath, amsfonts, amssymb, amsthm, graphicx, tikz, float, pdfpages, enumerate, mathrsfs, hyperref}\n%=========================================================\n\n\\begin{document}\n\n$0\n\n\\end{document}\n\n"))))

(add-to-list 'load-path "~/.emacs.d/lisp/")
(load "laas.el")
(add-hook 'LaTeX-mode-hook 'laas-mode)
(add-hook 'org-mode-hook 'laas-mode)

(use-package laas
  :config
  (aas-set-snippets 'laas-mode
    :cond #'texmathp ; expand only while in math. You can add some snippets here.
    "+dint" (lambda () (interactive)
            (yas-expand-snippet "\\int_{$1}^{$2} $0"))

  6. Execute the command doom/reload (or an equivalent command for your Emacs configuration) and restart Emacs.

  7. To edit the snippets, you can modify the file laas.el and change the lines which you have added to config.el.

Snippets list

Here you can find an overview of all snippets which are available after setting everything up as described above.

SnippetExpands toRemark
km$$ 
dm\begin{equation*}
\end{equation*}		 
alig\begin{align*}
\end{align*}		 
eqn\begin{equation}
\end{equation}		 
cite\cite{} 
cref\Cref{}If not using the Cleveref package, replace this by \ref{}.
eqref~\eqref{} 
latex\LaTeX 
TEMPLATEinserts a LaTeX template 
!=\ne  
==&=  
equiv\equiv  
app\approx  
sim\sim  
>=\ge  
ge\ge  
<=\le  
le\le  
>>\gg  
<<\ll  
+-\pm  
-+\mp  
**\cdot  
xx\times  
sr^2 
cb^3 
EE\exists  
AA\forall  
iff\iff  
=>\implies  
=<\impliedby  
lrar\leftrightarrow 
->\to  
<-\gets  
mapsto\mapsto  
inn\in  
notin\notin 
...\dots 
oo\infty 
::\colon  
||\mid 
<>\diamond  
dd\mathrm{d} 
par\partial 
,,\,  
inv^{-1} 
com^c 
cc\subset  
ceq\subseteq  
Nn\cap  
UU\cup  
nNn\bigcapnnn would conflict with the snippet nn which automatically adds the subscript _n.
uuu\bigcup 
VV\vee  
WW\wedge  
vvv\bigvee 
www\bigwedge 
OO\emptyset 
smi\setminus  
<!\triangleleft  
ell\ell 
quad\quad  
sum\sum 
prod\prod 
lim\lim 
linf\liminfCan’t use liminf because it would have the existinig snippet lim as a prefix.
lsup\limsup 
int\int 
oint\oint 
text\text{} 
bb\mathbb{} 
cal\mathcal{} 
scr\mathscr{} 
fra\mathfrak{} 
lr(\Bigl(\Bigr)\Bigl and \Bigr can of course be replaced by \left and \right. The closing ) should be inserted by smartparens, otherwise add it to the snippet.
lr[\Bigl[\Bigr] 
lr|\Bigl|\Bigr| 
set\{\} 
lrset\Bigl\{\Bigr\} 
lan\langle\rangle 
lrlan\Bigl\langle\Bigr\rangle 
floor\lfloor\rfloor 
ceil\lceil\rceil 
lrfloor\Bigl\lfloor\Bigr\rfloor 
lrceil\Bigl\lceil\Bigr\rceil 
norm\|\| 
lrnor\Bigl\| \Bigr\| 
sq\sqrt{} 
td^{} 
rd^{()} 
op\operatorname{} 
case\begin{cases}
\end{cases}		 
pmat\begin{pmatrix}
\end{pmatrix}		 
bmat\begin{bmatrix}
\end{bmatrix}		 
vmat\begin{vmatrix}
\end{vmatrix}		 
binom\binom{}{} 
dint\int_{}^{} 
,iint\iint_{} 
underset\underset{}{} 
overset\overset{}{} 
underbr\underbrace{}_{} 
overbr\overbrace{}^{} 
sin\sinTo write s \in and suppress this snippet, type s inn, inserting a space after the s.
cos\cos 
tan\tan 
sec\sec 
csc\csc 
cot\cot 
asin\arcsin 
acos\arccos 
atan\arctan 
asec\arcsec 
acsc\arccsc 
acot\arccot 
arsin\arsinVia this snippet, arsinh is replaced by \arsinh etc.
arcos\arcos 
artan\artan 
arsec\arsec 
arcsc\arcsc 
arcot\arcot 
min\min 
max\max 
sup\sup 
inf\inf 
grad\grad 
log\log 
exp\exp 
ln\ln 
star\star 
perp\perp 
pll\parallel 
circ\circ 
ker\ker 
coker\cokerYou might want to replace this by coer if coker interferes with evil-escape-key-sequence. Or use key-chord to remap escape to jk or kj. The same is true for .k, ..k and check below.
img\im 
coim\coim 
dim\dim 
codim\codim 
span\operatorname{span} 
dist\dist 
det\det 
deg\deg 
gcd\gcd 
lc\lcYou can also write lcm, which becomes \lcm.
sgn\sgn 
nabla\nabla 
grad\grad 
div\divg(custom command)
curl\curl(custom command)
rot\rot(custom command)
Re\Re(custom command)
Im\Im(custom command)
NN\mathbb{N} 
ZZ\mathbb{Z} 
QQ\mathbb{Q} 
RR\mathbb{R} 
CC\mathbb{C} 
TT\mathbb{T} 
DD\mathbb{D} 
FF\mathbb{F} 
KK\mathbb{K} 
PP\mathbb{P} 
XX\mathbb{E} 
.a\alpha 
.b\beta 
.g\gamma 
.d\delta 
.e\epsilon 
..e\varepsilon 
.z\zeta 
.h\eta 
.q\theta 
..q\vartheta 
.i\iota 
.k\kappa 
..k\varkappa 
.j\kappa 
..j\varkappa 
.l\lambda 
.m\mu 
.n\nu 
.x\xi 
.p\pi 
..p\varpi 
.r\rho 
..r\varrho 
.s\sigma 
..s\varsigma 
.t\tau 
.u\upsilon 
.f\phi 
..f\varphi 
.c\chi 
.y\psi 
.o\omega 
.w\omega 
.A\aleph 
.G\Gamma 
.D\Delta 
.Q\Theta 
.L\Lambda 
.X\Xi 
.P\Pi 
.S\Sigma 
.U\Upsilon 
.F\Phi 
.Y\Psi 
.O\Omega 
.W\Omega 
This post is licensed under CC BY 4.0 by the author.