This code shows how to write a modern Fortran interface to MPI which infers arguments that are already contained in the Fortran type itself, such as element type and count, and renders optional arguments when context is sufficient. For example, a root-less reduction maps to MPI_Allreduce and omitting the communicator argument causes MPI_COMM_WORLD to be used.

Formerly referred to as "galaxy brain", it has been renamed to havaita, which means detect or perceive in Finnish.