add a cool lua repl

lib/lua-linenoise/README.md

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+# lua-linenoise - Lua binding for the linenoise command line library
+
+Linenoise (https://github.com/antirez/linenoise) is a delightfully simple command
+line library.  This Lua module is simply a binding for it.
+
+The main Linenoise upstream has stagnated a bit, so this binding tracks https://github.com/yhirose/linenoise/tree/utf8-support, which
+includes things like UTF-8 support and ANSI terminal escape sequence detection.
+
+This repository also contains a Windows-compatible version of linenoise taken from MSOpenTech's [Windows port](https://github.com/MSOpenTech/redis) of redis.
+
+# Compilation
+
+If you use LuaRocks, you can run `luarocks make` on the latest rockspec.
+
+You can also build with make. When building this module using make, you may use the original linenoise source included in
+the repository, or you may set the Makefile variable `LIBLINENOISE` to override
+it:
+
+```sh
+make LIBLINENOISE=-llinenoise
+# OR:
+make LIBLINENOISE=/path/to/liblinenoise.a
+```
+
+You may need to change the value of the LN_EXPORT macro in lua-linenoise.c to the appropriate keyword to ensure the luaopen_linenoise function is exported properly (I don't know much about C or Unix-like systems, so I may have gotten it wrong).
+
+If you have Visual Studio 2012 (even the free Express version), you can compile this module with the Windows-compatible linenoise source using the included solution file (you'll need to edit the include paths and import library dependencies to match your configuration).
+
+If you prefer to compile using other tools, just link lua-linenoise.c with line-noise-windows/linenoise.c and line-noise-windows/win32fixes.c to create the Windows-compatible DLL.
+
+# Usage
+
+This library is a fairly thin wrapper over linenoise itself, so the function calls
+are named similarly.  I may develop a "porcelain" layer in the future.
+
+## L.linenoise(prompt)
+
+Prompts for a line of input, using *prompt* as the prompt string.  Returns nil if
+no more input is available; Returns nil and an error string if an error occurred.
+
+## L.historyadd(line)
+
+Adds *line* to the history list.
+
+## L.historysetmaxlen(length)
+
+Sets the history list size to *length*.
+
+## L.historysave(filename)
+
+Saves the history list to *filename*.
+
+## L.historyload(filename)
+
+Loads the history list from *filename*.
+
+## L.clearscreen()
+
+Clears the screen.
+
+## L.setcompletion(callback)
+
+Sets the completion callback.  This callback is called with two arguments:
+
+  * A completions object.  Use object:add or L.addcompletion to add a completion to this object.
+  * The current line of input.
+
+## L.addcompletion(completions, string)
+
+Adds *string* to the list of completions.
+
+All functions return nil on error; functions that don't have an obvious return value
+return true on success.
+
+## L.setmultiline(multiline)
+
+Enables multi-line mode if *multiline* is true, disables otherwise.
+
+## L.sethints(callback)
+
+Sets a hints callback to provide hint information on the right hand side of the
+prompt.  *calback* should be a function that takes a single parameter (a
+string, the line entered so far) and returns zero, one, or two values.  Zero
+values means no hint.  The first value may be *nil* for no hint, or a string
+value for a hint.  If the first value is a string, the second value may be a table
+with the *color* and *bold* keys - *color* is an ANSI terminal color code (such as
+those provided by the [lua-term](https://luarocks.org/modules/hoelzro/lua-term) colors
+module), whereas *bold* is a boolean indicating whether or not the hint should be printed
+as bold.
+
+## L.printkeycodes()
+
+Prints linenoise key codes.  Primarly used for debugging.
+
+## L.enableutf8()
+
+Enables UTF-8 handling.
+
+# Example
+
+```lua
+local L = require 'linenoise'
+local colors = require('term').colors -- optional
+-- L.clearscreen()
+print '----- Testing lua-linenoise! ------'
+local prompt, history = '? ', 'history.txt'
+L.historyload(history) -- load existing history
+L.setcompletion(function(completion,str)
+   if str == 'h' then
+    completion:add('help')
+    completion:add('halt')
+  end
+end)
+L.sethints(function(str)
+  if str == 'h' then
+    return ' bold hints in red', { color = colors.red, bold = true }
+  end
+end)
+
+L.enableutf8()
+
+local line, err = L.linenoise(prompt)
+while line do
+    if #line > 0 then
+        print(line:upper())
+        L.historyadd(line)
+        L.historysave(history) -- save every new line
+    end
+    line, err = L.linenoise(prompt)
+end
+if err then
+  print('An error occurred: ' .. err)
+end
+```