Action operator -- does not necessary means Spark action; but does mean running BLAS optimizer and writing down Spark graph lineage since last checkpointed DRM.
Distributed context, can be implicitly converted to operations on org.apache.mahout.math.drm. DistributedEngine.
R-like syntax for number of columns
R-like syntax for number of rows.
Basic spark DRM trait.
Since we already call the package "sparkbindings", I will not use stem "spark" with classes in this package. Spark backing is already implied.