Dear Domingo, I share the opinion that GMPL should remain a domain-specific language, and the additions that are being proposed would fit better in a general-purpose language.
This was the intention of the package python-glpk (discontinued after some internal changes in glpk), which has been captured and extended in AMPL's Python interface, AMPLPY: https://amplpy.readthedocs.io/en/latest/ Some examples there are similar to what you propose. Cheers, Joao Pedro
