Genome browser applications typically couple the visual representations to specific file formats and provide few customization options. GenomeSpy has a more abstract approach to visualization, providing combinatorial building blocks such as marks, transforms, and scales. Users can author novel visualizations that display the underlying data more effectively.
TODO: Quick introduction to view specifications. Meanwhile, have a look at Vega-Lite's view specification documentation to get the general idea.
A subset of Vega-Lite
The visualization grammar of GenomeSpy is a subset and a dialect of Vega-Lite. However, the goals of GenomeSpy and Vega-Lite are different – GenomeSpy is more domain specific and is intended for visualization and analysis of large datasets that contain genomic coordinates. GenomeSpy tries to faithfully follow Vega-Lite's grammar where practical. Thus, this documentation has many references to its documentation.