Snakemake mode provides support for editing Snakemake files. It builds on Python mode to provide fontification, indentation, and imenu indexing for Snakemake's rule blocks.

See also elpa-snakemake which provides an interface for running Snakemake commands.

elpa-snakemake-mode also includes support for highlighting embedded R code. See the snakemake-mode-setup-mmm function documentation for how.