It is a little hard to tell what the point of Terra is from the website; you should check out the PLDI paper for a better sense for what is going on http://terralang.org/publications.html (in particular, the example apps are telling: "Our Terra-based auto-tuner for BLAS routines performs within 20% of ATLAS, and our DSL for stencil computations runs 2.3x faster than hand-written C.")