Spack allows you to have several matrices of the same package installed. So, if you want to install Foobar, and you want one copy built with gcc and linked to

Spack allows you to have several matrices of the same package installed. So, if you want to install Foobar, and you want one copy built with gcc and linked to openmpi, one copy with llvm and linked to mpich, and three copies with the Intel compiler and three different versions of the Intel mpi libraries,spack can do that for you, and help manage your environment to ensure you are running the stack you intend. It's primary use is in supercomputing to make various optimizations available to users.