Here's an open source Python script i wrote a few years ago that allows you to type with your voice. It's based off of CMU Sphinx. The accuracy is almost certainly not as good as Dragon, and it doesn't have a macro facility, so you cannot code as fast as typing. I haven't improved it much over the past few years because my hands got better and i don't need it anymore.

https://sourceforge.net/projects/voicekey/ (tarball, includes language model) https://github.com/bshanks/voicekey (repo, does not include language model)