What became of Ihaka & Temple Lang's (2008) "Back to the Future"?

The only other environment you might have wanted to consider, since you are a fan of Prolog, would be the ECLiPSe environment, which is a Prolog environment dedicated to mathematical constraint programming. Matrices and arrays are part of the language (built-ins as they are known in Prolog). If you were willing to wrap C or C++ code, you could use any stats software written in those languages in ECLiPSe.

eclipseclp.org

ECLiPSe Main Features

Modern Fortran (anything after 1990) is also a worthy mention. There are loads of working Fortran code, but much of it isn’t organized well. There are a number of scientists and engineers working to make development in Fortran much easier, such as a standard library for various programming (including numerical progamming) tasks.

fortran-lang.org

The Fortran Programming Language — Fortran Programming Language

Fortran : High-performance parallel programming language