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-# [WIP] dial.nvim
+# dial.nvim
 
-increment/decrement plugin for Neovim.
+Extended increment/decrement plugin for Neovim. Mainly written in Lua.
+
+## Features
+
+* Increment/decrement decimal/hex/octal/binary natural integers
+* Increment/decrement decimal integers (including negative number)
+* Increment/decrement date
+* Increment/decrement alphabet
+* Increment/decrement hex colors
+* Increment/decrement markdown header
+
+## Installation
+
+If you use `vim-plug`:
+```
+Plug 'monaqa/dial.nvim'
+```
+
+## Usage
+
+This plugin does not provide any default keymap.
+To use this plugin, assign the plugin keymap to the key you like, as shown below:
+
+```
+nmap <C-a> <Plug>(dial-increment)
+nmap <C-x> <Plug>(dial-decrement)
+```
+
+## Configuration
+
+In this plugin, the target to increment/decrement is called **augend**.
+In `dial.nvim`, you can operate on multiple types of augend.
+
+To specify the list of augend you want to operate on, write the following code in your `.vimrc`:
+```
+lua << EOF
+local dial = require("dial")
+
+dial.searchlist = {
+    dial.augends.number.decimal,
+    dial.augends.number.hex,
+    dial.augends.number.binary,
+    dial.augends.date.date,
+    dial.augends.markup.markdown_header,
+}
+EOF
+```
+
+`dial.searchlist` is the list of augend,
+and `dial.augends` is a submodule that stores augend, which is provided by default.
+
+
+|Augend Name             |Explanation                                |Examples                           |
+|------------------------|-------------------------------------------|-----------------------------------|
+|`number.decimal`        |decimal natural number                     |`0`, `1`, ..., `9`, `10`, `11`, ...|
+|`number.hex`            |hex natural number                         |`0x00`, `0x3f3f`, ...              |
+|`number.octal`          |octal natural number                       |`000`, `011`, `024`, ...           |
+|`number.binary`         |binary natural number                      |`0b0101`, `0b11001111`, ...        |
+|`number.decimal_integer`|decimal integer (including negative number)|`0`, `314`, `-1592`, ...           |
+|`date.date`             |Date in the format `%Y/%m/%d`              |`2020/01/04`, `1970/01/01`, ...    |
+|`date.weekday_ja`       |Japanese weekday                           |`月`, `火`, ..., `土`, `日`        |
+|`char.alph_small`       |Lowercase alphabet letter (word)           |`a`, `b`, `c`, ..., `z`            |
+|`char.alph_capital`     |Uppercase alphabet letter (word)           |`A`, `B`, `C`, ..., `Z`            |
+|`color.hex`             |hex triplet                                |`#00ff00`, `#ababab`, ...          |
+|`markup.markdown_header`|Markdown Header                            |`#`, `##`, ..., `######`           |
+
+The list of currently enabled augends can be checked with `:DialShowSearchList` command.
+
+## User extension
+
+You can even define your own augend.
+Augend is a table that contains two fields (`name` and `desc`) and two methods (`find` and `add`).
+For example, the following code defines `my_augend`, which enables you to double or halve the natural number.
+
+```
+lua << EOF
+local dial = require("dial")
+
+local my_augend = {
+    name = "my_augend",
+    desc = "double or halve the number. (1 <-> 2 <-> 4 <-> 8 <-> ...)",
+
+    find = dial.augends.common.find_pattern("%d+"),
+    add = function(cursor, text, addend)
+        local n = tonumber(text)
+        n = math.floor(n * (2 ^ addend))
+        text = tostring(n)
+        cursor = #text
+        return cursor, text
+    end
+}
+
+dial.searchlist = {
+    my_augend
+}
+EOF
+```
+
+## TODO
+
+* Write help file
+* User-friendly error notification
+* Command for visual mode
+* Command for visual-line mode