#+TITLE: Migrating from Vim

* Table of Contents                     :TOC_5_gh:noexport:
- [[#purpose-of-this-document][Purpose of this document]]
- [[#philosophy][Philosophy]]
- [[#basic-orientation][Basic orientation]]
  - [[#terms][Terms]]
    - [[#modes-vs-states][Modes vs. States]]
    - [[#layers][Layers]]
    - [[#transient-states][Transient-states]]
  - [[#key-binding-conventions][Key binding conventions]]
  - [[#running-commands][Running commands]]
  - [[#buffer-and-window-management][Buffer and window management]]
    - [[#buffers][Buffers]]
      - [[#special-buffers][Special buffers]]
    - [[#windows][Windows]]
  - [[#files][Files]]
  - [[#the-help-system][The Help System]]
  - [[#exploring][Exploring]]
  - [[#regular-expression-syntax][Regular expression syntax]]
- [[#customization][Customization]]
  - [[#the-spacemacs-file][The .spacemacs file]]
  - [[#emacs-lisp][Emacs Lisp]]
    - [[#variables][Variables]]
    - [[#key-bindings][Key bindings]]
      - [[#bind-keys-to-a-macro][Bind keys to a macro]]
    - [[#functions][Functions]]
  - [[#activating-a-layer][Activating a Layer]]
  - [[#creating-a-layer][Creating a Layer]]
  - [[#installing-a-single-package][Installing a single package]]
  - [[#loading-packages][Loading packages]]
  - [[#uninstalling-a-package][Uninstalling a package]]
  - [[#common-tweaks][Common tweaks]]
    - [[#changing-the-escape-key][Changing the escape key]]
    - [[#changing-the-colorscheme][Changing the colorscheme]]
    - [[#nohlsearch][Nohlsearch]]
    - [[#sessions][Sessions]]
    - [[#navigating-using-visual-lines][Navigating using visual lines]]
- [[#other-useful-links][Other useful links]]

* Purpose of this document
This document is intended to supplement the Spacemacs documentation by bridging
the gap between vim and Spacemacs. While some information may be duplicated,
this does not replace the Spacemacs documentation. It is recommended that you
read both files to fully understand Spacemacs.

[[https://github.com/syl20bnr/spacemacs/blob/develop/doc/DOCUMENTATION.org][Spacemacs Documentation]]

* Philosophy
One misconception many vim users have is that Spacemacs is an Emacs /clone/ of
vim. Spacemacs does not seek to completely mimic the behavior of vim
everywhere, only when editing. You should not expect every vim command to be
available, although many are. You cannot use Vimscript to configure Spacemacs,
but who likes Vimscript anyway? It is important to understand that Spacemacs is
an attempt to improve on both vim and Emacs using the superior modal editing of
vim and the nicer configuration language of Emacs.

* Basic orientation
** Terms
Spacemacs uses some different terminology than vim, which can cause confusion
for new users. This section attempts to clear up any confusion.

*** Modes vs. States
In vim you have various editing modes like =insert mode= and =visual mode= to
manipulate text. In Emacs, we have [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/DOCUMENTATION.org#states][states]]. These are equivalent to vim modes.
For example, =evil-insert-state= is the same as =insert-mode= in vim.

A =minor-mode= in Emacs is like a feature that is activated. For example,
=aggressive-indent-mode= is a =minor-mode= that automatically indents code as you
type. It is important to know that there can be many =minor-modes= activated in a
buffer. Many Emacs packages work by providing a =minor-mode=. A =major-mode=
determines the editing behavior of Emacs in the current buffer. There is
generally a corresponding =major-mode= per filetype. An example of a =major-mode= is
=python-mode=, which provides python specific settings in python files. There is
only one =major-mode= per buffer.

*** Layers
Spacemacs has the concept of layers. Layers are similar to vim plugins. They
provide new features to use in Spacemacs. However, layers are often comprised of
several packages that integrate well with each other. For example, the =python=
layer includes support for auto-completion, documentation look-up, tests, and
much more by using several different packages. This keeps you from thinking
about what packages to install, and instead worry about what features you want.
More information on layers can be found in the [[#customization][customization]] section and in the
[[https://github.com/syl20bnr/spacemacs/blob/develop/doc/DOCUMENTATION.org#configuration-layers][documentation]]. There is also a more in-depth guide on writing layers [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/LAYERS.org][here]].

*** Transient-states
Spacemacs provides a special functionality called transient-states. Transient-states
allow similar commands to be run in succession without repeatedly pressing the
~<Leader>~ key. Transient-states are usually triggered by using a key binding with the
following pattern: ~<Leader> <group> .~ where group is the category the
transient-state falls under. When in a transient-state you will see documentation at the
bottom of your window. To exit a transient-state press ~q~.

#+CAPTION: Transient-state documentation window

[[file:img/spacemacs-scale-transient-state.png]]

** Key binding conventions
Spacemacs uses ~SPC~ as its ~<Leader>~ key. This document will use ~SPC~ to refer to
the ~<Leader>~ key. All key bindings are mnemonic and are organized under the
~<Leader>~ key. For example, the key bindings for language-specific commands are
always under the ~SPC m~ prefix. A full list of conventions used in Spacemacs is
[[https://github.com/syl20bnr/spacemacs/blob/develop/doc/CONVENTIONS.org][here]]. Note that all key bindings can be changed.

Spacemacs uses [[https://github.com/justbur/emacs-which-key][which-key]] to show available key bindings after a delay:

#+CAPTION: Which-key window

[[file:img/which-key.png]]

** Running commands
Emacs commands can be run using ~SPC SPC~. This will pop up a buffer using [[https://github.com/emacs-helm/helm][Helm]]
which can be used to run any Emacs command. You can also run many ex commands
using ~:~, just like in vim.

Note: You can run Emacs interactive commands using ~:~, but you cannot run ex
commands using ~SPC SPC~.

** Buffer and window management
*** Buffers
Buffers in Emacs and vim are essentially the same. The key bindings for buffers
are located under the ~SPC b~ prefix.

| Key binding               | Function                                             |
|---------------------------+------------------------------------------------------|
| ~SPC b b <buffer-name>~   | Create a buffer named =<buffer-name>=.               |
| ~SPC b b~                 | Search through open buffers and recent files.        |
| ~SPC b n~ or ~:bnext~     | Switch to the next buffer. (See [[#special-buffers][Special buffers]])     |
| ~SPC b p~ or ~:bprevious~ | Switch to the previous buffer. (See [[#special-buffers][Special buffers]]) |
| ~SPC b d~ or ~:bdelete~   | Kill current buffer.                                 |
| ~SPC b C-S-d~             | Kill buffers using a regular expression.             |
| ~SPC b C-d~               | Kill all buffers except the current buffer.          |
| ~SPC b .~                 | Buffer transient-state.                              |

**** Special buffers
By default Emacs creates a lot of buffers that most people will never need, like
=*Messages*=. Spacemacs automatically ignores these when using these
key bindings. More information can be found [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/DOCUMENTATION.org#special-buffers][here]].

*** Windows
Windows are like splits in vim. They are useful for editing multiple files at
once. All window key bindings are under the ~SPC w~ prefix.

| Key binding            | Function                             |
|------------------------+--------------------------------------|
| ~SPC w v~ or ~:vsplit~ | Opens a vertical split on the right. |
| ~SPC w s~ or ~:split~  | Opens a horizontal split below.      |
| ~SPC w h/j/k/l~        | Navigate among windows.              |
| ~SPC w H/J/K/L~        | Move the current window.             |
| ~SPC w .~              | Window transient-state.              |

** Files
All file commands in Spacemacs are available under the ~SPC f~ prefix.

| Key binding       | Function                                                     |
|-------------------+--------------------------------------------------------------|
| ~SPC f f~         | Opens a buffer to search for files in the current directory. |
| ~SPC f r~         | Opens a buffer to search through recently opened files.      |
| ~SPC f s~ or ~:w~ | Save the current file.                                       |
| ~:x~              | Save the current file and quit.                              |
| ~:e <file>~       | Open =<file>=                                                |

** The Help System
Emacs has an extensive help system. All key bindings under the ~SPC h d~ prefix
allow convenient access to the help system. The most important of these
keybindings are ~SPC h d f~, ~SPC h d k~, and ~SPC h d v~. There is also the
~SPC <f1>~ key binding which allows you to search for documentation.

| Key binding | Function                                                                         |
|-------------+----------------------------------------------------------------------------------|
| ~SPC h d f~ | Prompts for a function and shows its documentation.                              |
| ~SPC h d k~ | Prompts for a key binding and shows what it is bound to.                         |
| ~SPC h d v~ | Prompts for a variable and shows its documentation and current value.            |
| ~SPC <f1>~  | Searches for a command, function, variable, or face and shows its documentation. |

Whenever, you see weird behavior or want to know what something does, these
functions are the first thing you should refer to.

** Exploring
There are a few ways to explore the functionality of Spacemacs. One is to read
the [[https://github.com/syl20bnr/spacemacs][source code]] on GitHub. You can begin to feel your way around Emacs Lisp and
how Spacemacs works this way. You can also use the following key bindings to
explore:

| Key binding | Function                                                      |
|-------------+---------------------------------------------------------------|
| ~SPC h SPC~ | Lists all layers and allows you to view files from the layer. |
| ~SPC ?~     | Lists all key bindings.                                       |

** Regular expression syntax
One thing that might catch you off guard is the difference in regex syntax
between Vim and Emacs. In Emacs, even when you search under =evil-mode=
with the =/= key, you'll be using the Emacs flavor of regular expression,
instead of the Vim one.

Some idiosyncrasies of Elisp regex:
- You need to additionally escape some symbols such as:
  - backslash ~\~ :: ~\\~
  - alternation ~|~ :: ~\|~
  - grouping ~(~ and ~)~ :: ~\(~ and ~\)~
  - counting ~{~ and ~}~ :: ~\{~ and ~\}~
- ~\s~ begins a [[https://www.emacswiki.org/emacs/RegularExpression][syntax class]]. Whitespaces are denoted as ~\s-~ instead of ~\s~.
- Use ~[0-9]~ or ~[:digit:]~ instead of ~\d~ to denote digits.

For more details, refer to [[https://www.emacswiki.org/emacs/RegularExpression][The EmacsWiki]], this [[https://stackoverflow.com/questions/1946352/comparison-table-for-emacs-regexp-and-perl-compatible-regular-expression-pcre][SO question]]
and [[https://github.com/joddie/pcre2el][this tool]] which converts PCRE regex to Emacs regex.

* Customization
** The .spacemacs file
When you first start spacemacs, you will be prompted to choose an editing style.
If you are reading this, you likely want to choose the vim style. A =.spacemacs=
file will be created with the appropriate style selected. Most trivial
configuration will go in this file.

There are four top-level functions in the file: =dotspacemacs/layers=,
=dotspacemacs/init=, =dotspacemacs/user-init= and =dotspacemacs/user-config=.
The =dotspacemacs/layers= function exist only to enable and disable layers and
packages. The =dotspacemacs/init= function is run before anything else during
startup and contains Spacemacs settings. You will never need to touch this
function except to change default Spacemacs settings.
The =dotspacemacs/user-init= function is also run before anything else and
contains user specific configuration. The =dotspacemacs/user-config= function
is the one you will use the most. This is where you define any user configuration.

| Key binding | Function                                                                 |
|-------------+--------------------------------------------------------------------------|
| ~SPC f e d~ | Open your =.spacemacs=                                                   |
| ~SPC f e D~ | Update your =.spacemacs= manually using a diff with the default template |

** Emacs Lisp
This section introduces a few emacs lisp functions that are needed to configure
Spacemacs. For a more detailed look at the language, see [[http://learnxinyminutes.com/docs/elisp/][this]] link. If you
really want to learn everything there is about emacs lisp, use the info page
found at ~SPC h i elisp RET~.

*** Variables
Setting variables is the most common way to customize the behavior of Spacemacs.
The syntax is simple:

#+BEGIN_SRC emacs-lisp
  (setq variable value) ; Syntax
  ;; Setting variables example
  (setq variable1 t ; True
        variable2 nil ; False
        variable3 '("A" "list" "of" "things"))
#+END_SRC

*** Key bindings
Defining key bindings is something that almost everyone will want to do. The
built-in =define-key= function is the best way to do that.

#+BEGIN_SRC emacs-lisp
  (define-key map new-keybinding function) ; Syntax
  ;; Map H to go to the previous buffer in normal mode
  (define-key evil-normal-state-map (kbd "H") 'previous-buffer)
#+END_SRC

The map is the keymap you want to bind the key in. Most of the time you will use
=evil-<state-name>-state-map=. These correspond to different =evil-mode= states.
For example, using =evil-insert-state-map= maps the key binding in insert mode.

To map ~<Leader>~ key bindings, use the =spacemacs/set-leader-keys= function.

#+BEGIN_SRC emacs-lisp
  (spacemacs/set-leader-keys key function) ; Syntax
  ;; Map killing a buffer to <Leader> b c
  (spacemacs/set-leader-keys "bc" 'spacemacs/kill-this-buffer)
  ;; Map opening a link to <Leader> o l only in org-mode (works for any major-mode)
  (spacemacs/set-leader-keys-for-major-mode 'org-mode
    "ol" 'org-open-at-point)
#+END_SRC

**** Bind keys to a macro
#+BEGIN_SRC emacs-lisp
  ;; H goes to beginning of the line
  (define-key evil-normal-state-map (kbd "H") (kbd "^"))
#+END_SRC

Bind keys to multiple other keys.

For example: To open a newline above, but stay on the current line.

The remapping in Vim:

#+BEGIN_SRC vimrc
  nmap <S-Enter> O<Esc>j
#+END_SRC

source: [[https://vim.fandom.com/wiki/Insert_newline_without_entering_insert_mode]]

The equivalent remapping in Spac/Emacs:

#+BEGIN_SRC emacs-lisp
  ;; S-return adds a newline above
  (define-key evil-normal-state-map (kbd "S-<return>") (kbd "O <escape> j"))
#+END_SRC

*** Functions
You may occasionally want to define a function to do a more complex
customization. The syntax is simple:

#+BEGIN_SRC emacs-lisp
  (defun func-name (arg1 arg2)
    "docstring"
    ;; Body
    )

  ;; Calling a function
  (func-name arg1 arg2)
#+END_SRC

Here is an example of a function that is useful in real life:

#+BEGIN_SRC emacs-lisp
  ;; This snippet allows you to run clang-format before saving
  ;; given the current file as the correct filetype.
  ;; This relies on the c-c++ layer being enabled.
  (defun clang-format-for-filetype ()
    "Run clang-format if the current file has a file extensions
  in the filetypes list."
    (let ((filetypes '("c" "cpp")))
      (when (member (file-name-extension (buffer-file-name)) filetypes)
        (clang-format-buffer))))

  ;; See http://www.gnu.org/software/emacs/manual/html_node/emacs/Hooks.html for
  ;; what this line means
  (add-hook 'before-save-hook 'clang-format-for-filetype)
#+END_SRC

** Activating a Layer
As said in the terms section, layers provide an easy way to add features.
Activating a layer is done in the =.spacemacs= file. In the file search for the
=dotspacemacs-configuration-layers= variable. By default, it should look like
this:

#+BEGIN_SRC emacs-lisp
  (defun dotspacemacs/layers ()
    (setq-default
     ;; ...
     dotspacemacs-configuration-layers '(;; auto-completion
                                         ;; better-defaults
                                         emacs-lisp
                                         ;; (git :variables
                                         ;;      git-gutter-use-fringe t)
                                         ;; markdown
                                         ;; org
                                         ;; syntax-checking
                                         )))
#+END_SRC

You can uncomment these suggested layers by deleting the semi-colons for a nice
out-of-the-box experience. To add a layer, add its name to the list and restart
Emacs or press ~SPC f e R~. To view all layers and their documentation use
~SPC h SPC~.

** Creating a Layer
To group configuration or when configuration doesn't fit well in your
=.spacemacs= file, you can create a configuration layer. Spacemacs provides a
builtin command to generate the layer boilerplate:
~SPC SPC configuration-layer/create-layer RET~. This generates a folder that
looks like this:

#+BEGIN_EXAMPLE
  [layer-name]
    |__ [local]*
    | |__ [example-mode-1]
    | |     ...
    | |__ [example-mode-n]
    |__ config.el*
    |__ funcs.el*
    |__ keybindings.el*
    |__ packages.el

  [] = directory
  * = not created by the command
#+END_EXAMPLE

The =packages.el= file contains a list of packages that you can install in the
variable =<layer-name>-packages=. Any package that is available on the [[http://melpa.org][MELPA]]
repository can be added to the list. A list can also exclude packages using the
=:excluded t= property.
Each package requires a function to initialize it. The function /must/ be named
with this pattern: =<layer-name>/init-<package-name>=. This function contains
configuration for the package. There are also =pre/post-init= functions to
execute code before or after a package loads. It would look like this:

#+BEGIN_SRC emacs-lisp
  (setq layer-name-packages '(example-package
                              ;; This layer uninstalls example-package-2
                              ;; by setting the :excluded property to true (t)
                              (example-package-2 :excluded t)))

  (defun layer-name/post-init-package ()
    ;; Add configuration to a package in another layer here
    )

  (defun layer-name/init-example-package ()
    ;; Configuration for example-package goes here
    )
#+END_SRC

**Note**: Only one layer can have a =init= function for a package. If you want
to override the configuration of a package in another layer, use a
=<layer-name>/pre-init= function in addition to [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/LAYERS.org#use-package-hooks][use-package hooks]].

If a package is not available on MELPA, you must use a local package or a
package recipe. For more details see [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/LAYERS.org#anatomy-of-a-layer][anatomy of a layer]].

Make sure you [[#activating-a-layer][add]] your layer to your =.spacemacs= file and restart to
activate it.

A detailed description of the loading process and how layers work can be found in
the [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/LAYERS.org][configuration layers documentation.]]

** Installing a single package
Sometimes creating a layer is a bit overkill. Maybe you just want one package
and don't want to maintain a whole layer. Spacemacs provides a variable in the
=dotspacemacs/layers= function in =.spacemacs= called
=dotspacemacs-additional-packages=. Just add a package name to the list and it
will be installed when you restart. Loading the package is covered in the next
[[#loading-packages][section]].

** Loading packages
Ever wonder how Spacemacs can load over a 100 packages in just a few seconds?
Such low loading times must require some kind of unreadable black magic that no
one can understand. Thanks to [[https://github.com/jwiegley/use-package][use-package]], this is not true. It is a package
that allows easy lazy-loading and configuration of packages. Here are the basics
to using it:

#+BEGIN_SRC emacs-lisp
  ;; Basic form of use-package declaration. The :defer t tells use-package to
  ;; try to lazy load the package.
  (use-package package-name
    :defer t)
  ;; The :init section is run before the package loads. The :config section is
  ;; run after the package loads
  (use-package package-name
    :defer t
    :init
    (progn
      ;; Change some variables
      (setq variable1 t variable2 nil)
      ;; Define a function
      (defun foo ()
        (message "%s" "Hello, World!")))
    :config
    (progn
      ;; Calling a function that is defined when the package loads
      (function-defined-when-package-loads)))
#+END_SRC

This is just a very basic overview of =use-package=. There are many other ways
to control how a package loads using it that aren't covered here.

** Uninstalling a package
Spacemacs provides a variable in the =dotspacemacs/init= function in
=.spacemacs= called =dotspacemacs-excluded-packages=. Just add a package name to
the list and it will be uninstalled when you restart.

** Common tweaks
This section is for things many will want to change. All of these settings go in
the =dotspacemacs/user-config= function in your =.spacemacs= unless otherwise noted.

*** Changing the escape key
Spacemacs uses [[https://github.com/syl20bnr/evil-escape][evil-escape]] to
allow escaping from many =major-modes= with one key binding. You can customize
the variable in your =dotspacemacs/user-config= like this:

#+BEGIN_SRC emacs-lisp
  (defun dotspacemacs/user-config ()
    ;; ...
    ;; Set escape keybinding to "jk"
    (setq-default evil-escape-key-sequence "jk"))
#+END_SRC

More documentation is found in the =evil-escape= [[https://github.com/syl20bnr/evil-escape/blob/master/README.md][README]].

*** Changing the colorscheme
The =.spacemacs= file contains the =dotspacemacs-themes= variable in the
=dotspacemacs/init= function. This is a list of themes that can be cycled
through with the ~SPC T n~ key binding. The first theme in the list is the one
that is loaded at startup. Here is an example:

#+BEGIN_SRC emacs-lisp
  (defun dotspacemacs/init
      ;; Darktooth theme is the default theme
      ;; Each theme is automatically installed.
      ;; Note that we drop the -theme from the package name.
      ;; Ex. darktooth-theme -> darktooth
      (setq-default dotspacemacs-themes '(darktooth
                                          soothe
                                          gotham)))
#+END_SRC

All installed themes can be listed and chosen using the ~SPC T h~ key binding.

*** Nohlsearch
Spacemacs emulates the default vim behavior which highlights search results even
when you are not navigating between them. You can use ~SPC s c~ or ~:nohlsearch~
to disable search result highlighting.

To disable the result highlighting when it is not needed anymore automatically,
you can [[#uninstalling-a-package][uninstall]] the =evil-search-highlight-persist= package.

*** Sessions
Spacemacs does not automatically restore your windows and buffers when you
reopen it. If you use vim sessions regularly you may want to set
=dotspacemacs-auto-resume-layouts= to =t= in your =.spacemacs=.

*** Navigating using visual lines
Spacemacs uses the vim default of navigating by actual lines, even if they are
wrapped. If you want ~j~ and ~k~ to behave like ~g j~ and ~g k~, add this to
your =.spacemacs=:

#+BEGIN_SRC emacs-lisp
  (define-key evil-normal-state-map (kbd "j") 'evil-next-visual-line)
  (define-key evil-normal-state-map (kbd "k") 'evil-previous-visual-line)
#+END_SRC

* Other useful links
- [[https://www.gnu.org/software/emacs/manual/emacs.html][Emacs Manual]]
- [[https://github.com/syl20bnr/spacemacs/blob/develop/doc/DOCUMENTATION.org][Spacemacs Documentation]]
- [[http://ian.mccowan.space/2015/04/07/Spacemacs/][Spacemacs: A Vimmer's Emacs Prerequisites]]
  - Note: The article refers to ~SPC b s~ as the key binding to switch buffers.
    It is ~SPC b b~
- [[http://thume.ca/howto/2015/03/07/configuring-spacemacs-a-tutorial/][Configuring Spacemacs: A Tutorial]]
- [[https://web.archive.org/web/20190423065450/https://juanjoalvarez.net/es/detail/2014/sep/19/vim-emacsevil-chaotic-migration-guide/][From Vim to Emacs+Evil chaotic migration guide]]
