OpenSees started with Tcl and is now riding the wave of Python’s popularity. But, it’s not too soon to ask which language the next OpenSees interpreter will use.
In my opinion, Julia is the front runner.
According to its Wikipedia page, the name refers to something “so complicated or unusual that it exceeds the limits of one’s understanding”. While this description applies to some OpenSees analyses, visualizations, and tutorials I have seen online, the programming language itself should not be unusable.
So, although the language can be translated into C using basic substitutions and pointer arithmetic, I doubt we will see OpenSeesBf any time soon.