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Dubious for App Engine

See the published demo:

Introducing Dubious

This is s starter project for Mirah on App Engine. Dubious provide a way to build apps in Mirah, with conventions familiar to Rails developers. Mirah has no runtime dependencies, everything is compiled ahead-of-time. Mirah apps have none of the initialization costs associated with JRuby. Dubious supports ERb and has a simple datastore adapter that uses a syntax similar to DataMapper.

Introducing Mirah

Mirah is a new language with Ruby-inspired syntax that compiles to JVM bytecode. Mirah is statically typed, with local type inference, and a simple macro system. The goal is to make Mirah as expressive as Ruby without introducing any runtime library and while maintaining Java's level of performance. Just write code that looks like Ruby, but reference the Java docs to find out what method calls to make. Mirah uses the Java type system. Join the duby-dev mailing list to get involved:

Setup the Mirah development environment

Fetch App Engine Java SDK and JRuby, then install them into /usr/local

Make sure the appengine tools are executable

sudo chmod a+x /usr/local/appengine-java-sdk-1.3.5/bin/*.sh

Now git clone bitescript, mirah and dubious to your drive

mkdir -p ~/mystuff; cd ~/mystuff
git clone
git clone
git clone

Edit .bash_profile to find these tools

export JRUBY_HOME=/usr/local/jruby-1.5.1
export MIRAH_HOME=~/mystuff/mirah
export APPENGINE_JAVA_SDK=/usr/local/appengine-java-sdk-1.3.5

Verify tools are configured properly, and check to see that script/ has the correct path to the SDK.

which mirah
which jruby

Developing your App

Until be have generators, just start by altering the main dubious app.

cd ~/mystuff/dubious

There are two ways to develop the app. The first way is to run the build script each time you make a change. The new way is to use the Rakefile. If you are using jruby's rake, the task will watch for source file changes and update the running class files. Otherwise, you need to restart the server when you have changes.

Use the Original Scripts

Compile the Mirah files and populate the WEB-INF/lib dir


Run the app locally


Edit the app-id in app.yaml, then publish to


Use the New Rakefile

Populate the WEB-INF/lib dir


Run the app locally

jruby -S rake server

Edit the app-id in app.yaml, then publish to

jruby -S rake publish

Apache License 2.0

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