update README

Author: hone

README.md

@@ -1,12 +1,14 @@
 # mruby CLI
-A utility for setting up a CLI with [mruby](https://www.mruby.org) for compiling binaries for Linux, OS X, and Windows.
+A utility for setting up a CLI with [mruby](https://www.mruby.org) that compiles binaries to Linux, OS X, and Windows.
 
-## Docker Setup
-You'll need [Docker](https://docs.docker.com/installation/) and [Docker Compose](https://docs.docker.com/compose/install/) installed first.
+## Prequisites
+You'll need the following installed and in your `PATH`:
 
-## Building a CLI app
-This assumes you have a copy of the `mruby-cli` binary in your `PATH`.
+* [mruby-cli](https://github.com/hone/mruby-cli/releases)
+* [Docker](https://docs.docker.com/installation/)
+* [Docker Compose](https://docs.docker.com/compose/install/)
 
+## Building a CLI app
 To generate a new mruby CLI, there's a `--setup` option.
 
 ```sh
@@ -36,6 +38,35 @@ root@3da278e931fc:/home/mruby/code# mruby/build/host/bin/hello_world
 Hello World
 ```
 
+## Hello World
+
+Building the canonical hello world example in mruby-cli is quite simple. The two files of note from the generate skeleton are `mrblib/hello_world.rb` and `mrbgem.rake`. The CLI hooks into the `__main__` method defined here and passes all the arguments as `argv`.
+
+`mrblib/hello_world.rb`:
+```ruby
+def __main__(argv)
+  puts "Hello World"
+end
+```
+
+### Dependencies
+The rubygems equivalent is mrbgems. [mgem-list](https://github.com/mruby/mgem-list) contains a list of mgems you can pull from. By default mruby does not include everything in the kitchen sink like MRI. This means to even get `puts`, we need to include the `mruby-print`. The list of core gems can be found [here](https://github.com/mruby/mruby/tree/master/mrbgems). Adding dependencies is simple, you just need to add a line near the bottom of your `mrbgem.rake` with the two arguments: name and where it comes from.
+
+`mrbgem.rake`:
+```ruby
+MRuby::Gem::Specification.new('hello_world') do |spec|
+  spec.license = 'MIT'
+  spec.author  = 'Terence Lee'
+  spec.summary = 'Hello World'
+  spec.bins    = ['hello_world']
+
+  spec.add_dependency 'mruby-print', :core => 'mruby-print'
+  spec.add_dependency 'mruby-mtest', :mgem => 'mruby-test'
+end
+```
+### CLI Architecture
+The app is built from two parts a C wrapper in `tools/` and a mruby part in `mrblib/`. The C wrapper is fairly minimal and executes the `__main__` method in mruby and instantiates ARGV and passes it to the mruby code. The rest of the CLI is written in mruby. You can't have subfolders in `mrblib/` but you can have as many files in `mrblib/`. All these files are precompiled into mruby bytecode The build tool for mruby is written in CRuby (MRI).
+
 ### Testing
 By default, `mruby-cli` generates two kinds of tests: mtest and bintest.
 
@@ -53,8 +84,9 @@ These are integration tests, are written in CRuby (MRI), and go in the `bintest/
 $ docker-compose run bintest
 ```
 
-### CLI Architecture
-The app is built from two parts a C wrapper in `tools/` and a mruby part in `mrblib/`. The C wrapper is fairly minimal and executes the `__main__` method in mruby and instantiates ARGV and passes it to the mruby code. The rest of the CLI is written in mruby. The build tool for mruby is written in CRuby (MRI).
+## Examples
+* `mruby-cli` itself is an app generated by `mruby-cli`, so you can explore this repo on how to build one.
+* [mruby-eso-research](https://github.com/hone/mruby-eso-research) - an app for managing crafting research in Elder Scrolls Online. It uses YAML as the data store.
 
 ## mruby-cli Development
 This app is built as a mruby-cli app, so you just need to run: `docker-compose run compile` and find the binaries in the appropriate directories.