Add kmonad to update my keyboard
diff --git a/modules/kmonad.nix b/modules/kmonad.nix
new file mode 100644
index 0000000..ef5793b
--- /dev/null
+++ b/modules/kmonad.nix
@@ -0,0 +1,11 @@
+{ kmonad, ... }: {
+  imports = [ kmonad.nixosModules.default ];
+
+  config.services.kmonad = {
+    enable = false;
+    keyboards.laptop-internal = {
+      device = "/dev/input/by-path/platform-i8042-serio-0-event-kbd";
+      config = builtins.readFile ./kmonad/config.kbd;
+    };
+  };
+}
diff --git a/modules/kmonad/config.kbd b/modules/kmonad/config.kbd
new file mode 100644
index 0000000..7a67153
--- /dev/null
+++ b/modules/kmonad/config.kbd
@@ -0,0 +1,951 @@
+#| --------------------------------------------------------------------------
+
+                              KMonad: Guided tour
+
+  Welcome to the KMonad configuration tutorial. This document aims to explain:
+  1. The configuration syntax
+  2. The required information
+  3. All possible configuration options
+
+  This document should be a runnable configuration, so with some tweaks to the
+  `defcfg` block (see below) you should be able to try out all the examples
+  interactively.
+
+  -------------------------------------------------------------------------- |#
+
+
+#| --------------------------------------------------------------------------
+
+                     Basic syntax: comments and parentheses
+
+  KMonad's configuration language is styled on various lisps, like scheme or
+  Common Lisp. In a lisp, every statement is entered between '(' and ')'s. If
+  you are more used to Fortan style languages (python, ruby, C, Java, etc.), the
+  change is quite straightforward: the function name moves into the parentheses,
+  and you don't use commas to separate arguments. I.e.
+
+  This:     my_function(a, 3, "Alakazam")
+  Becomes:  (my_function a 3 "Alakazam")
+
+  The reason for this is because Lisp-style languages are very easy to parse and
+  write syntax-highlighters for.
+
+  We also provide standard Lisp syntax for comments:
+  - block comments between: #| and its reverse
+  - line comments following: ;;
+
+  Unlike standard lisp, a single ; does not denote a comment, but instead the
+  keycode for semicolon.
+
+  Also, as you might have noticed, whitespace is possible anywhere.
+
+  To check for syntax errors while editing, invoke kmonad with the -d option.
+  -------------------------------------------------------------------------- |#
+
+
+#| --------------------------------------------------------------------------
+                         Necessary: the `defcfg` block
+
+  There are a few bits of information that are required to be present in a
+  KMonad configuration file. One of these is the existence of exactly 1 `defcfg`
+  statement. This statement is used to customize various configuration settings.
+  Many of these settings have default values, but a minimal definition must
+  include at least an 'input' field and an 'output' field. These describe how
+  KMonad captures its inputs and how it emits its outputs.
+
+  First, let's go over the optional, non-OS specific settings. Currently there is
+  only 2:
+
+  - fallthrough: `true` or `false`, defaults to `false`
+
+    KMonad catches input events and tries to match them to various handlers. If
+    it cannot match an event to any handler (for example, if it isn't included
+    in the `defsrc` block, or if it is, but the current keymap does not map any
+    buttons to it), then the event gets quietly ignored. If `fallthrough` is set
+    to `true`, any unhandled events simply get reemitted.
+
+  - allow-cmd: `true` or `false`, defaults to `false`
+
+    If this is set to `false`, any action that runs a shell-command will simply
+    log to `stdout` without ever running (log-level info). Don't ever enable
+    this on a configuration that you do not trust, because:
+
+      (cmd-button "rm -rf ~/*")
+
+    is a thing. For more information on the `cmd-button' function, see the
+    section on Command buttons below.
+
+  There are also some optional OS specific settings that we support:
+
+  - `cmp-seq': KEY, defaults to `RightAlt' (Linux X11 specific)
+
+    This sets your compose key for Unicode input. For more information, as well
+    as a workaround to also make this work on windows, see the section on
+    Compose-key sequences below.
+
+  - `cmp-seq-delay': NUMBER (in milliseconds)
+
+    This sets a delay between each pressed key in a compose-key sequence.  Some
+    environments may have troubles recognizing the key sequence if it's pressed
+    too rapidly; if you experience any problems in this direction, you can try
+    setting this value to `5' or `10' and see if that helps.
+
+  Secondly, let's go over how to specify the `input` and `output` fields of a
+  `defcfg` block. This differs between OS'es, and so do the capabilities of
+  these interfaces.
+
+
+  -- Linux ------
+
+  In Linux we deal with input by performing an ioctl-grab on a specific
+  device-file. This allows us to hook KMonad on the input of exactly 1 keyboard,
+  and allows you to run multiple instances of KMonad for different keyboards. We
+  make an input using:
+    (device-file "/dev/input/by-id/my-keyboard-kbd")
+
+  NOTE: Any valid path to a device-file will work, but it is recommended to use
+  the 'by-id' directory, since these names will not change if you replug the
+  device.
+
+  We deal with output by creating a 'uinput' device. This requires that the
+  'uinput' kernel module is loaded. The easiest way to ensure this is by calling
+  'sudo modprobe uinput'. We create a uinput device using:
+    (uinput-sink "name" "optional post-init command")
+
+
+  -- Windows ----
+
+  In Windows we do not get such fine-grained control. We use a low-level
+  keyboard hook to intercept all non-injected keyboard events. There is
+  currently an open issue to improve the C-bindings used to capture windows
+  keyevents, and if you have a better way to approach this issue, help is deeply
+  appreciated. You specify a windows input using:
+    (low-level-hook)
+
+  Similarly, the output in Windows lacks the fine-grained control. We use the
+  SendEvent API to emit key events directly to Windows. Since these are
+  'artificial' events we won't end up catching them again by the
+  `low-level-hook`. It is very likely that KMonad does not play well with other
+  programs that capture keyboard input like AHK. You specify windows output using:
+    (send-event-sink)
+
+
+  -- Mac OS -----
+
+  For Mac questions I suggest filing an issue and tagging @thoelze1, he wrote
+  the MacOS API. However, input using:
+    (iokit-name "optional product string")
+
+  By default this should grab all keyboards, however if a product string is
+  provided, KMonad will only capture those devices that match the provided
+  product string. If you would like to provide a product string, you can run
+  `make; ./list-keyboards' in c_src/mac to list the product strings of all
+  connected keyboards.
+
+  You initialize output on MacOS using:
+    (kext)
+
+  -------------------------------------------------------------------------- |#
+
+(defcfg
+  ;; For Linux
+  input  (device-file "/dev/input/by-id/usb-04d9_daskeyboard-event-kbd")
+  output (uinput-sink "My KMonad output"
+    ;; To understand the importance of the following line, see the section on
+    ;; Compose-key sequences at the near-bottom of this file.
+    "/run/current-system/sw/bin/sleep 1 && /run/current-system/sw/bin/setxkbmap -option compose:ralt")
+  cmp-seq ralt    ;; Set the compose key to `RightAlt'
+  cmp-seq-delay 5 ;; 5ms delay between each compose-key sequence press
+
+  ;; For Windows
+  ;; input  (low-level-hook)
+  ;; output (send-event-sink)
+
+  ;; For MacOS
+  ;; input  (iokit-name "my-keyboard-product-string")
+  ;; output (kext)
+
+  ;; Comment this if you want unhandled events not to be emitted
+  fallthrough true
+
+  ;; Set this to false to disable any command-execution in KMonad
+  allow-cmd true
+)
+
+
+#| --------------------------------------------------------------------------
+                         Necessary: the `defsrc` block
+
+  It is difficult to explain the `defsrc` block without immediately going into
+  `deflayer` blocks as well. Essentially, KMonad maps input-events to various
+  internal actions, many of which generate output events. The `defsrc` block
+  explains the layout on which we specify our `deflayer`s down the line.
+
+  It is important to realize that the `defsrc` block doesn't *necessarily* have
+  to coincide with your actual input keyboard. You can specify a full 100%
+  `defsrc` block, but only use a 40% keyboard. This will mean that every
+  `deflayer` you specify will also have to match your 100% `defsrc`, and that
+  your actual keyboard would be physically unable to trigger about 60% of your
+  keymap, but it would be perfectly valid syntax.
+
+  The dual of this (and more useful) is that it is also perfectly valid to only
+  specify that part of your keyboard in `defsrc` that you want to remap. If you
+  use a 100% keyboard, but don't want to remap the numpad at all you can simply
+  leave the numpad out of your `defsrc`, and it should work just fine. In that
+  particular case you probably want to set `fallthrough` to `true` in your
+  `defcfg` block though.
+
+  In the future we would like to provide support for multiple, named `defsrc`
+  blocks, so that it becomes easier to specify various layers for just the
+  numpad, for example, but at the moment any more or less than 1 `defsrc` block
+  will result in an error.
+
+  The layouting in the `defsrc` block is completely free, whitespace simply gets
+  ignored. We strive to provide a name for every keycode that is no longer than
+  4 characters, so we find that laying out your keymap in columns of 5 works out
+  quite nicely (although wider columns will allow for more informative aliases,
+  see below).
+
+  Most keycodes should be obvious. If you are unsure, check
+  './src/KMonad/Keyboard/Keycode.hs'. Every Keycode has a name corresponding to
+  its Keycode name, but all lower-case and with the 'Key' prefix removed. There
+  are also various aliases for Keycodes starting around line 350. If you are
+  trying to bind a key and there is not a 4-letter alias, please file an issue,
+  or better yet, a pull-request, and it will be added promptly.
+
+  Also, you can consult './keymap/template/' for various input templates to use
+  directly or to look up keycodes by position. Here we use the input-template
+  for 'us_ansi_60.kbd'
+
+  -------------------------------------------------------------------------- |#
+
+(defsrc
+  grv  1    2    3    4    5    6    7    8    9    0    -    =    bspc
+  tab  q    w    e    r    t    y    u    i    o    p    [    ]    \
+  caps a    s    d    f    g    h    j    k    l    ;    '    ret
+  lsft z    x    c    v    b    n    m    ,    .    /    rsft
+  lctl lmet lalt           spc            ralt rmet cmp  rctl
+)
+
+
+#| --------------------------------------------------------------------------
+                        Optional : `defalias` statements
+
+  KMonad will let you specify some very specific, crazy buttons. These
+  definitions can get pretty long, though, and would make `deflayer` blocks
+  nearly impossible to read. Therefore we provide the ability to alias names to
+  these buttons, to keep the actual `deflayer` statements orderly.
+
+  A `defalias` can contain any number of aliases, and it can refer backwards or
+  forwards to layers without issue. The only sequencing that needs to be kept in
+  mind is that a `defalias` cannot refer forward to another `defalias` that is
+  not yet defined.
+
+  Here we define a few aliases, but we will define more later. Notice that we
+  try to only use 3 letter names for aliases. If that is not enough to be clear,
+  consider widening all columns to 6 or 7 characters (or be content with a messy
+  config).
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  num  (layer-toggle numbers) ;; Bind num to a button that switches to a layer
+  kil  C-A-del                ;; Bind kil to a button that Ctrl-Alt-deletes
+)
+
+
+#| NOTE: The above code could just as easily have been written as:
+(defalias num (layer-toggle numbers))
+(defalias kil C-A-del)
+|#
+
+
+#| --------------------------------------------------------------------------
+                     Necessary: at least 1 `deflayer` block
+
+  As explained in the `defsrc` section, a `deflayer` will define a button for
+  each corresponding entry in the `defsrc` definition. A `deflayer` statement
+  consists of the `deflayer` keyword, followed by the name used to identify this
+  layer, followed by N 'statements-that-evaluate-to-a-button', where N is
+  exactly how many entries are defined in the `defsrc` statement.
+
+  It is also important to mention that the 'keymap' in KMonad is modelled as a
+  stack of layers (just like in QMK). When an event is registered we look in the
+  top-most layer for a handler. If we don't find one we try the next layer, and
+  then the next.
+
+  Exactly what 'evaluates-to-a-button' will be expanded on in more detail below.
+  There are very many different specialist buttons in KMonad that we will touch
+  upon. However, for now, these 4 are a good place to begin:
+
+  1. Any keycode evaluates to a button that, on press, emits the press of that
+     keycode, and on release, emits the release of that keycode. Just a 'normal'
+     button. The exception is '\', which gets used as an escape character. Use
+     '\\' instead. Other characters that need to be escaped to match the literal
+     character are '(', ')', and '_'.
+
+  2. An @-prefixed name evaluates to an alias lookup. We named two buttons in
+     the `defalias` block above, we could now refer to these buttons using
+     `@num` and `@kil`. This is also why we only use alias-names no longer than
+     3 characters in this tutorial. Also, note that we are already referencing
+     some aliases that have not yet been defined, this is not an issue.
+
+  3. The '_' character evaluates to transparent. I.e. no handler for that
+     key-event in this layer, causing this event to be handed down the layer
+     stack to perhaps be handled by the next layer.
+
+  4. The 'XX' character evaluates to blocked. I.e. no action bound to that
+     key-event in this layer, but do actually catch event, preventing any
+     underlying layer from handling it.
+
+  Finally, it is important to note that the *first* `deflayer` statement in a
+  KMonad config will be the layer that is active when KMonad starts up.
+
+  -------------------------------------------------------------------------- |#
+
+
+(deflayer qwerty
+  grv  1    2    3    4    5    6    7    8    9    0    -    =    bspc
+  tab  q    w    e    r    t    y    u    i    o    p    [    ]    \
+  caps a    s    d    f    g    h    j    k    l    ;    '    ret
+  lsft z    x    c    v    b    n    m    ,    .    /    rsft
+  lctl @num lalt           spc            ralt rmet @sym @tst
+)
+
+
+#| --------------------------------------------------------------------------
+                     Optional: as many layers as you please
+
+  We had already defined `num` as referring to a `(layer-toggle numbers)`. We
+  will get into layer-manipulation soon, but first, let's just create a second
+  layer that overlays a numpad under our right-hand.
+
+  To easily specify layers it is highly recommended to create an empty
+  `deflayer` statement as a comment at the top of your config, so you can simply
+  copy-paste this template. There are also various empty layer templates
+  available in the './keymap/template' directory.
+
+  -------------------------------------------------------------------------- |#
+
+(deflayer numbers
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    XX   /    7    8    9    -    _    _    _
+  _    _    _    _    _    XX   *    4    5    6    +    _    _
+  _    _    \(   \)   .    XX   0    1    2    3    _    _
+  _    _    _              _              _    _    _    _
+)
+
+
+#| --------------------------------------------------------------------------
+                          Optional: modded buttons
+
+  Let's start by exploring the various special buttons that are supported by
+  KMonad by looking at 'modded' buttons, that is to say, buttons that activate
+  some kind of 'mod', then perform some button, and finally release that 'mod'
+  again.
+
+  We have already seen an example of this style of button, our `kil` button is
+  one such button. Let's look at it in more detail:
+    C-A-del
+
+  This looks like a simple declarative statement, but it's helpful to realize
+  that is simply syntactic sugar around 2 function calls. This statement is
+  equivalent to:
+    (around ctl (around alt del))
+
+  This highlights a core design principle in KMonad: we try to provide very
+  simple buttons, and then we provide rules and functions for combining them
+  into new buttons. Although note: still very much a work in progress.
+
+  So, looking at this statement:
+    (around foo bar)
+
+  Here, `around` is a function that takes two buttons and creates a new button.
+  This new button will, on a press, first press foo, then press bar, and on a
+  release first release bar, and then foo. Once created, this new button can be
+  passed to anything in KMonad that expects a button.
+
+  We have already seen other examples of modded buttons, \(, \), *, and +. There
+  are no Keycodes for these buttons in KMonad, but they are buttons. They simply
+  evaluate to `(around lsft x)`. All shifted numbers have their corresponding
+  characters, the same is true for all capitals, and < > : ~ " | { } \_ + and ?.
+
+  To wrap up 'modded-buttons', let's look back at C-A-del. We have 8 variants:
+  C- : (around lctl X)
+  A- : (around lalt X)
+  M- : (around lmet X)
+  S- : (around lsft X)
+
+  Then RC-, RA-, RM-, and RS- behave exactly the same, except using the
+  right-modifier.
+
+  These can be combined however you please:
+    C-A-M-S-x          ;; Perfectly valid
+    C-%                ;; Perfectly valid: same as C-S-5
+    C-RC-RA-A-M-S-RS-m ;; Sure, but why would you?
+
+  Also, note that although we provide special syntax for certain modifiers,
+  these buttons are in no way 'special' in KMonad. There is no concept of 'modifier'.
+    (around a (around b c)) ;; Perfectly valid
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+
+  ;; Something useful
+  cpy C-c
+  pst C-v
+  cut C-x
+
+  ;; Something silly
+  md1 (around a (around b c))    ;; abc
+  md2 (around a (around lsft b)) ;; aB
+  md3 C-A-M-S-l
+  md4 (around % b)               ;; BEWARE: %B, not %b, do you see why?
+)
+
+#| --------------------------------------------------------------------------
+                          Optional: sticky keys
+
+  KMonad also support so called "sticky keys".  These are keys that will
+  behave as if they were pressed after just tapping them.  This behaviour
+  wears off after the next button is pressed, which makes them ideal for
+  things like a quick control or shift.  For example, tapping a sticky and
+  then pressing `abc' will result in `Abc'.
+
+  You can create these keys with the `sticky-key' keyword:
+
+    (defalias
+      slc (sticky-key 500 lctl))
+
+  The number after `sticky-key' is the timeout you want, in milliseconds.  If
+  a key is tapped and that time has passed, it won't act like it's pressed
+  down when we receive the next keypress.
+
+  It is also possible to combine sticky keys.  For example, to
+  get a sticky shift+control you can do
+
+    (defalias
+      ssc (around
+           (sticky-key 500 lsft)
+           (sticky-key 500 lctl)))
+
+  -------------------------------------------------------------------------- |#
+
+;; Let's make both shift keys sticky
+(defalias
+  sl (sticky-key 300 lsft)
+  sr (sticky-key 300 rsft))
+
+
+;; Now we define the 'tst' button as opening and closing a bunch of layers at
+;; the same time. If you understand why this works, you're starting to grok
+;; KMonad.
+;;
+;; Explanation: we define a bunch of testing-layers with buttons to illustrate
+;; the various options in KMonad. Each of these layers makes sure to have its
+;; buttons not overlap with the buttons from the other layers, and specifies all
+;; its other buttons as transparent. When we use the nested `around` statement,
+;; whenever we push the button linked to '@tst' (check `qwerty` layer, we bind
+;; it to `rctl`), any button we press when holding `rctl` will be pressed in the
+;; context of those 4 layers overlayed on the stack. When we release `rctl`, all
+;; these layers will be popped again.
+(defalias tst (around (layer-toggle macro-test)
+                (around (layer-toggle layer-test)
+                  (around (layer-toggle around-next-test)
+                    (around (layer-toggle command-test)
+                            (layer-toggle modded-test))))))
+
+(deflayer modded-test
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    @md4 _    _    _    _    _    _    _    _    _    _    _
+  _    _    @md1 @md2 @md3 _    _    _    _    _    _    _    _
+  _    _    @cut @cpy @pst _    _    _    _    _    _    _
+  _    _    _              _              _    _    _    _
+)
+
+#| --------------------------------------------------------------------------
+                              Optional: tap-macros
+
+  Let's look at a button we haven't seen yet, tap-macros.
+
+  `tap-macro` is a function that takes an arbitrary number of buttons and
+  returns a new button. When this new button is pressed it rapidly taps all its
+  stored buttons in quick succesion except for its last button, which it only
+  presses. This last button gets released when the `tap-macro` gets released.
+
+  There are two ways to define a `tap-macro`, using the `tap-macro` function
+  directly, or through the #() syntactic sugar. Both evaluate to exactly the
+  same button.
+
+    (tap-macro K M o n a d)
+    #(K M o n a d)
+
+  If you are going to use a `tap-macro` to perform a sequence of actions inside
+  some program you probably want to include short pauses between inputs to give
+  the program time to register all the key-presses. Therefore we also provide
+  the 'pause' function, which simply pauses processing for a certain amount of
+  milliseconds. Pauses can be created like this:
+
+    (pause 20)
+    P20
+
+  You can also pause between each key stroke by specifying the `:delay' keyword,
+  as well as a time in ms, at the end of a `tap-macro':
+
+    (tap-macro K M o n a d :delay 5)
+    #(K M o n a d :delay 5)
+
+  The above would be equivalent to e.g.
+
+    (tap-macro K P5 M P5 o P5 n P5 a P5 d)
+
+  The `tap-macro-release` is like `tap-macro`, except that it
+  waits to press the last button when the `tap-macro-release`
+  gets released.  It might be useful when combined with a
+  footswitch that sends keybooard scan codes.
+
+    (tap-macro-release i K M o n a d esc)
+
+  WARNING: DO NOT STORE YOUR PASSWORDS IN PLAIN TEXT OR IN YOUR KEYBOARD
+
+  I know it might be tempting to store your password as a macro, but there are 2
+  huge risks:
+  1. You accidentally leak your config and expose your password
+  2. Anyone who knows about the button can get clear-text representation of your
+  password with any text editor, shell, or text-input field.
+
+  Support for triggering shell commands directly from KMonad is described in the
+  command buttons section below.
+
+  This concludes this public service announcement.
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  mc1 #(K M o n a d)
+  mc2 #(C-c P50 A-tab P50 C-v) ;; Careful, this might do something
+  mc3 #(P200 h P150 4 P100 > < P50 > < P20 0 r z 1 ! 1 ! !)
+  mc4 (tap-macro a (pause 50) @md2 (pause 50) c)
+  mc5 (tap-macro-release esc esc esc)
+  mc6 #(@mc3 spc @mc3 spc @mc3)
+)
+
+(deflayer macro-test
+  _    @mc1 @mc2 @mc3 @mc4 @mc5 @mc6 _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _              _              _    _    _    _
+)
+
+
+#| --------------------------------------------------------------------------
+                          Optional: layer manipulation
+
+  You have already seen the basics of layer-manipulation. The `layer-toggle`
+  button. This button adds a layer to the top of KMonad's layer stack when
+  pressed, and removes it again when released. There are a number of other ways
+  to manipulate the layer stack, some safer than others. Let's go through all of
+  them from safest to least safe:
+
+  `layer-toggle` works as described before, 2 things to note:
+  1. If you are confused or worried about pressing a key, changing layers, and
+     then releasing a key and this causing issues: don't be. KMonad handles
+     presses and releases in very different ways. Presses get passed directly to
+     the stacked keymap as previously described. When a KMonad button has its
+     press-action triggered, it then registers a callback that will catch its
+     own release before we ever touch the keymap. This guarantees that the
+     button triggered by the press of X *will be* the button whose release is
+     triggered by the release of X (the release of X might trigger other things
+     as well, but that is besides the point.)
+  2. If `layer-toggle` can only ever add and then necessarily remove 1 layer
+     from the stack, then it will never cause a permanent change, and is
+     perfectly safe.
+
+  `layer-delay`, once pressed, temporarily switches to some layer for some
+  milliseconds. Just like `layer-toggle` this will never permanently mess-up the
+  layer stack. This button was initially implemented to provide some
+  'leader-key' style behavior. Although I think in the future better solutions
+  will be available. For now this will temporarily add a layer to the top of the
+  stack:
+    (layer-delay 500 my-layer)
+
+  `layer-next`, once pressed, primes KMonad to handle the next press from some
+  arbitrary layer. This aims to fill the same usecase as `layer-delay`: the
+  beginnings of 'leader-key' style behavior. I think this whole button will get
+  deleted soon, because the more general `around-next` now exists (see below)
+  and this is nothing more than:
+    (around-next (layer-toggle layer-name))
+  Until then though, use `layer-next` like this:
+    (layer-next layer-name)
+
+  `layer-switch`: change the base-layer of KMonad. As described at the top of
+  this document, the first `deflayer` statement is the layer that is active when
+  KMonad starts. Since `layer-toggle` can only ever add on and remove from the
+  top of that, it can never change the base-layer. The following button will
+  unregister the bottom-most layer of the keymap, and replace it with another
+  layer.
+    (layer-switch my-layer)
+
+  This is where things start getting potentially dangerous (i.e. get KMonad into
+  an unusuable state until a restart has occured). It is perfectly possible to
+  switch into a layer that you can never get out of. Or worse, you could
+  theoretically have a layer full of only `XX`s and switch into that, rendering
+  your keyboard unuseable until you somehow manage to kill KMonad (without using
+  your keyboard).
+
+  However, when handled well, `layer-switch` is very useful, letting you switch
+  between 'modes' for your keyboard. I have a tiny keyboard with a weird keymap,
+  but I switch into a simple 'qwerty' keymap shifted 1 button to the right for
+  gaming. Just make sure that any 'mode' you switch into has a button that
+  allows you to switch back out of the 'mode' (or content yourself restarting
+  KMonad somehow).
+
+  `layer-add` and `layer-rem`. This is where you can very quickly cause yourself
+  a big headache. Originally I didn't expose these operations, but someone
+  wanted to use them, and I am not one to deny someone else a chainsaw. As the
+  names might give away:
+    (layer-add name) ;; Add a layer to the top of the stack
+    (layer-rem name) ;; Remove a layer by name (noop if no such layer)
+
+  To use `layer-add` and `layer-rem` well, you should take a moment to think
+  about how to create a layout that will prevent you from getting into
+  situations where you enter a key-configuration you cannot get out of again.
+  These two operations together, however, are very useful for activating a
+  permanent overlay for a while. This technique is illustrated in the tap-hold
+  overlay a bit further down.
+
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+
+  yah (layer-toggle asking-for-trouble) ;; Completely safe
+  nah (layer-add asking-for-trouble)    ;; Completely unsafe
+
+  ld1 (layer-delay 500 numbers) ;; One way to get a leader-key
+  ld2 (layer-next numbers)      ;; Another way to get a leader key
+
+  ;; NOTE, this is safe because both `qwerty` and `colemak` contain the `@tst`
+  ;; button which will get us to the `layer-test` layer, which itself contains
+  ;; both `@qwe` and `@col`.
+  qwe (layer-switch qwerty) ;; Set qwerty as the base layer
+  col (layer-switch colemak) ;; Set colemak as the base layer
+)
+(deflayer layer-test
+  @qwe _    _    _    _    _    _    _    _    _    _    @add _    @nah
+  @col _    _    _    _    _    _    _    _    _    _    _    _    @yah
+  _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    @ld1 @ld2 _
+  _    _    _              _              _    _    _    _
+)
+
+;; Exactly like qwerty, but with the letters switched around
+(deflayer colemak
+  grv  1    2    3    4    5    6    7    8    9    0    -    =    bspc
+  tab  q    w    f    p    g    j    l    u    y    ;    [    ]    \
+  @xcp a    r    s    t    d    h    n    e    i    o    '    ret
+  @sl  z    x    c    v    b    k    m    ,    .    /    @sr
+  lctl @num lalt           spc            ralt rmet @sym @tst
+)
+
+(defalias lol #(: - D))
+
+;; Contrived example
+(deflayer asking-for-trouble
+  @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol
+  @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol
+  @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol
+  @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol @lol
+  @lol @lol @lol           @lol           @lol @lol @lol @lol
+)
+
+;; One way to safely use layer-add and layer-rem: the button bound to layer-add
+;; is the same button bound to layer-rem in the layer that `add` adds to the
+;; stack. I.e., it becomes impossible to add or remove multiple copies of a
+;; layer.
+(defalias
+  add (layer-add multi-overlay) ;; multi-overlay is defined in the next
+  rem (layer-rem multi-overlay) ;; section below this
+  )
+
+#| --------------------------------------------------------------------------
+                          Optional: Multi-use buttons
+
+  Perhaps one of the most useful features of KMonad, where a lot of work has
+  gone into, but also an area with many buttons that are ever so slightly
+  different. The naming and structuring of these buttons might change sometime
+  soon, but for now, this is what there is.
+
+  For the next section being able to talk about examples is going to be handy,
+  so consider the following scenario and mini-language that will be the same
+  between scenarios.
+    - We have some button `foo` that will be different between scenarios
+    - `foo` is bound to 'Esc' on the input keyboard
+    - the letters a s d f are bound to themselves
+    - Px  signifies the press of button x on the keyboard
+    - Rx  signifies the release of said button
+    - Tx  signifies the sequential and near instantaneous press and release of x
+    - 100 signifies 100ms pass
+
+  So for example:
+    Tesc Ta:
+      tap of 'Esc' (triggering `foo`), tap of 'a' triggering `a`
+    Pesc 100 Ta Tb Resc:
+      press of 'Esc', 100ms pause, tap of 'a', tap of 'b', release of 'Esc'
+
+  The `tap-next` button takes 2 buttons, one for tapping, one for holding, and
+  combines them into a single button. When pressed, if the next event is its own
+  release, we tap the 'tapping' button. In all other cases we first press the
+  'holding' button then we handle the event. Then when the `tap-next` gets
+  released, we release the 'holding' button.
+
+  So, using our mini-language, we set foo to:
+    (tap-next x lsft)
+  Then:
+    Tesc            -> x
+    Tesc Ta         -> xa
+    Pesc Ta Resc    -> A
+    Pesc Ta Tr Resc -> AR
+
+  The `tap-hold` button is very similar to `tap-next` (a theme, trust me). The
+  difference lies in how the decision is made whether to tap or hold. A
+  `tap-hold` waits for a particular timeout, if the `tap-hold` is released
+  anywhere before that moment we execute a tap immediately. If the timeout
+  occurs and the `tap-hold` is still held, we switch to holding mode.
+
+  The additional feature of a `tap-hold` is that it pauses event-processing
+  until it makes its decision and then rolls back processing when the decision
+  has been made.
+
+  So, again with the mini-language, we set foo to:
+    (tap-hold 200 x lsft) ;; Like tap-next, but with a 200ms timeout
+  Then:
+    Tesc            -> x
+    Tesc Ta         -> xa
+    Pesc 300 a      -> A (the moment you press a)
+    Pesc a 300      -> A (after 200 ms)
+    Pesc a 100 Resc -> xa (both happening immediately on Resc)
+
+  The `tap-hold-next` button is a combination of the previous 2. Essentially,
+  think of it as a `tap-next` button, but it also switches to held after a
+  period of time. This is useful, because if you have a (tap-next ret ctl) for
+  example, and you press it thinking you want to press C-v, but then you change
+  your mind, you now cannot release the button without triggering a 'ret', that
+  you then have to backspace. With the `tap-hold-next` button, you simply
+  outwait the delay, and you're good. I see no benefit of `tap-next` over
+  `tap-hold-next` with a decent timeout value.
+
+  You can use the `:timeout-button` keyword to specify a button other than the
+  hold button which should be held when the timeout expires. For example, we
+  can construct a button which types one x when tapped, multiple x's when held,
+  and yet still acts as shift when another button is pressed before the timeout
+  expires. So, using the minilanguage and foo as:
+    (tap-hold-next 200 x lsft :timeout-button x)
+  Then:
+    Tesc           -> Tx
+    Pesc 100 a     -> A (the moment you press a)
+    Pesc 5000 Resc -> xxxxxxx (some number of auto-repeated x's)
+
+  Note that KMonad does not itself auto-repeat the key. In this last example,
+  KMonad emits 200 Px 4800 Rx, and the operating system's auto-repeat feature,
+  if any, emits multiple x's because it sees that the x key is held for 4800 ms.
+
+  The `tap-next-release` is like `tap-next`, except it decides whether to tap or
+  hold based on the next release of a key that was *not* pressed before us. This
+  also performs rollback like `tap-hold`. So, using the minilanguage and foo as:
+    (tap-next-release x lsft)
+  Then:
+    Tesc Ta         -> xa
+    Pa Pesc Ra Resc -> ax (because 'a' was already pressed when we started, so
+                           foo decides it is tapping)
+    Pesc Ta Resc    -> A (because a was pressed *and* released after we started,
+                          so foo decides it is holding)
+
+  These increasingly stranger buttons are, I think, coming from the stubborn
+  drive of some of my more eccentric (and I mean that in the most positive way)
+  users to make typing with modifiers on the home-row more comfortable.
+  Especially layouts that encourage a lot of rolling motions are nicer to use
+  with the `release` style buttons.
+
+  The `tap-hold-next-release` (notice a trend?) is just like `tap-next-release`,
+  but it comes with an additional timeout that, just like `tap-hold-next` will
+  jump into holding-mode after a timeout.
+
+  I honestly think that `tap-hold-next-release`, although it seems the most
+  complicated, probably is the most comfortable to use. But I've put all of them
+  in a testing layer down below, so give them a go and see what is nice.
+
+  -------------------------------------------------------------------------- |#
+
+
+(defalias
+  xtn (tap-next x lsft)         ;; Shift that does 'x' on tap
+  xth (tap-hold 400 x lsft)     ;; Long delay for easier testing
+  thn (tap-hold-next 400 x lsft)
+  tnr (tap-next-release x lsft)
+  tnh (tap-hold-next-release 2000 x lsft)
+
+  ;; Used it the colemak layer
+  xcp (tap-hold-next 400 esc ctl)
+)
+
+;; Some of the buttons used here are defined in the next section
+(deflayer multi-overlay
+  @mt  _    _    _    _    _    _    _    _    _    _    _    @rem _
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  @thn _    _    _    _    _    _    _    _    _    _    _    _
+  @xtn _    _    _    _    _    _    _    _    _    _    @xth
+  @tnr _    _              _              _    _    _    @tnh
+)
+
+
+#| --------------------------------------------------------------------------
+                              Optional: Multi-tap
+
+  Besides the tap-hold style buttons there is another multi-use button (with.
+  only 1 variant, at the moment). The `multi-tap`.
+
+  A `multi-tap` codes for different buttons depending on how often it is tapped.
+  It is defined by a series of delays and buttons, followed by a last button
+  without delay. As long as you tap the `multi-tap` within the delay specified,
+  it will jump to the next button. Once the delay is exceeded the selected
+  button is pressed. If the last button in the list is reached, it is
+  immediately pressed. When another key is pressed down while we're tapping,
+  `multi-tap' also immediately exits and taps the current button.
+
+  Note that you can actually hold the button, so in the below example, going:
+  tap-tap-hold (wait 300ms) will get you a pressed c, until you release again.
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  mt  (multi-tap 300 a 300 b 300 c 300 d e))
+
+
+#| --------------------------------------------------------------------------
+                              Optional: Around-next
+
+  The `around-next` function creates a button that primes KMonad to perform the
+  next button-press inside some context. This could be the context of 'having
+  Shift pressed' or 'being inside some layer' or, less usefully, 'having d
+  pressed'. It is a more general and powerful version of `layer-next`.
+
+  There is also an `around-next-timeout` button that does the same thing as
+  `around-next`, except that if some other button press is not detected within
+  some timeout, some other button is tapped. This can be used to create a
+  leader-key that simply times out (by passing a non-button), or a key that can
+  still function as a normal key, but also as a leader key when used slowly.
+
+  I think expansion of this button-style is probably the future of leader-key,
+  hydra-style functionality support in KMonad.
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  ns  (around-next sft)  ;; Shift the next press
+  nnm (around-next @num) ;; Perform next press in numbers layer
+  ntm (around-next-timeout 500 sft XX)
+
+
+)
+
+(deflayer around-next-test
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  @ns  _    _    _    _    _    _    _    _    _    _    _    _
+  @nnm _    _    _    _    _    _    _    _    _    _    _
+  @ntm _    _              _              _    _    _    _
+)
+
+#| --------------------------------------------------------------------------
+                        Optional: Compose-key sequences
+
+  Compose-key sequences are series of button-presses that your operating system
+  will interpret as the insertion of a special character, like accented
+  characters, or various special-languages. In that sense, they are just
+  syntactic sugar for keyboard macros.
+
+  To get this to work on Linux you will need to set your compose-key with a tool
+  like `setxkbmap', as well as tell kmonad that information. See the `defcfg'
+  block at the top of this file for a working example. Note that you need to
+  wait ever so slightly for the keyboard to register with linux before the
+  command gets executed, that's why the `sleep 1`. Also, note that all the
+  `/run/current-system' stuff is because the author uses NixOS. Just find a
+  shell-command that will:
+
+    1. Sleep a moment
+    2. Set the compose-key to your desired key
+
+  Please be aware that what `setxkbmap' calls the `menu' key is not actually the
+  `menu' key! If you want to use the often suggested
+
+      setxkbmap -option compose:menu
+
+  you will have to set your compose key within kmonad to `compose' and not
+  `menu'.
+
+  After this, this should work out of the box under Linux. Windows does not
+  recognize the same compose-key sequences, but WinCompose will make most of the
+  sequences line up with KMonad: http://wincompose.info/
+  This has not in any way been tested on Mac.
+
+  In addition to hard-coded symbols, we also provide 'uncompleted' macros. Since
+  a compose-key sequence is literally just a series of keystrokes, we can omit
+  the last one, and enter the sequence for 'add an umlaut' and let the user then
+  press some letter to add this umlaut to. These are created using the `+"`
+  syntax.
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  sym (layer-toggle symbols)
+
+)
+
+(deflayer symbols
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    ä    é    ©    _    _    _    _    _    _    _    _    _    _
+  _    +'   +~   +`   +^   _    _    _    _    _    _    _    _
+  _    +"   +,   _    _    _    _    _    _    _    _    _
+  _    _    _              _              _    _    _    _)
+
+
+#| --------------------------------------------------------------------------
+                        Optional: Command buttons
+
+  Currently we also provide the ability to launch arbitrary shell-commands from
+  inside kmonad. These commands are simply handed off to the command-shell
+  without any further checking or waiting.
+
+  NOTE: currently only tested on Linux, but should work on any platform, as long
+  as the command is valid for that platform.
+
+  The `cmd-button' function takes two arguments, the second one of which is
+  optional. These represent the commands to be executed on pressing and
+  releasing the button respectively.
+
+  BEWARE: never run anyone's configuration without looking at it. You wouldn't
+  want to push:
+
+    (cmd-button "rm -rf ~/*") ;; Delete all this user's data
+
+
+  -------------------------------------------------------------------------- |#
+
+(defalias
+  dat (cmd-button "date >> /tmp/kmonad_example.txt")   ;; Append date to tmpfile
+  pth (cmd-button "echo $PATH > /tmp/kmonad_path.txt") ;; Write out PATH
+  ;; `dat' on press and `pth' on release
+  bth (cmd-button "date >> /tmp/kmonad_example.txt"
+                  "echo $PATH > /tmp/kmonad_path.txt")
+)
+
+(deflayer command-test
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    _    _    _    _
+  _    _    _    _    _    _    _    _    _    @dat @pth _
+  _    _    _              _              _    _    _    _
+)