Development through a C++ interpreter (Cling) as opposed to a standard compiler is an amazing leap in productivity and window into the newest features of C++. This post tells you how to get your own bleeding-edge C++ interpreter built right on top of the development version of LLVM. We give you a repeatable procedure on top of Amazon EC2.

With our prescribed steps in place, you can always have a development version of a C++ interpreter in place, allowing quick testing and investigation of LLVM's newest features. You also get a development environment for Cling if interested in contributing to the project or learning how its innards push C++ along.

<h3>Background</h3>

Astoundingly, there <strong>is</strong> such a thing as a C++ interpreter! Thus, if you're interested in sticking to C for speed and efficiency, you're not confined to the code-compile-run-debug workflow. Living outside such a workflow lends jumps in productivity and a unique angle through which to see C++.

Development of a serious C++ interpreter <a href="http://www.linuxjournal.com/article/2895" target="_blank">was undertaken by the wizards at CERN</a> starting at around 1995. (You might recognize this group as searchers <a href="http://home.web.cern.ch/topics/higgs-boson" target="_blank">for the Higgs Boson</a>). The C++ interpreter was dubbed <a href="https://root.cern.ch/drupal/content/cint" target="_blank">CINT</a> and was designed to support a major data analysis and visualization package known as <a href="https://root.cern.ch/drupal/" target="_blank">ROOT</a> (screenshot below).

<img src="http://root.cern.ch/drupal/sites/default/files/images/alieve-esd-pbpb.png" alt="A ROOT screenshot being driven by a C++ interpreter (CINT). CINT is not a toy implementation - rather it is used to investigate the fabric of the universe." />

Over the last 20 years, CINT fell behind the evolving C++ language. In response, workers at CERN began work on a replacement for CINT dubbed Cling with the strategy of leveraging LLVM to stay up to date with the growing C++ specification. Up until recently, the project has been rather nascent, but now is at the point where its functionality and build system make Cling worthwhile for use and contribution.

<h3>Building for x86</h3>

We present a build procedure leveraging Amazon EC2. By using the cloud, you are guaranteed to use the exact Linux version and hardware capabilities that we did in testing. We assume that you have an Amazon EC2 account and that you are willing to spend around two dollars on compute resources.

1. Create an <pre>m3.xlarge</pre> instance with the Debian Jessie community ABI 