Context Accurately relating code authorship to commit frequency over multiple
software revisions is a complex task. Most of the navigation tools found in
common source code versioning clients are often too rigid to formulate specific
queries and adequately present results of such queries. Questions related to
evolution asked by software engineers are therefore challenging at answering
using common Git clients. 

Objective This paper explores the use of stacked adjacency matrices and a
domain specific language to produce tailored interactive visualizations for
software evolution exploration. We are able to support some classical software
evolution tasks using short and concise scripts using our language. 

Method We propose a domain-specific language to stack adjacency matrices and
produce scalable and interactive visualizations. Our language and
visualizations are evaluated using two independent controlled experiments and
closely observing participants. 

Results We made the following findings: (i) participants are able to express
sophisticated queries using our domain-specific language and visualizations,
(ii) participants perform better than GitHub's visualizations to answer a set
of questions. 

Conclusion Our visual and scripting environment performs better than GitHub's
visualizations at extracting software evolution information.