A macro-language for energy system modeling in R. Describe an energy system as R objects (commodities, technologies, supply, demand, storage, trade), compile it into a capacity-expansion and dispatch optimization model, solve it on one of four interchangeable backends (GLPK/MathProg, Julia/JuMP, Python/Pyomo, or GAMS), and analyze tidy results with built-in tools for levelized costs, technology reports, and plotting.