Discrete (or mixed) conditions

[polsys]

Originally, conditioning variables were always continuous. #87 will add support for discrete-discrete variables and discrete conditions. However, this leaves many cases unimplemented:

• Continuous variables, discrete condition (interpreting condition as continuous might work, though)
• Discrete variables, continuous condition (shouldn't be too hard to implement)
• Mixed discrete-continuous condition (how hard, and how necessary?)

In table form:

	No condition	Discrete	Continuous	Mixed
Discrete-discrete	🆕	🆕	❌	❌
Discrete-continuous	✔️	❌	✔️	❌
Continuous-continuous	✔️	❌	✔️	❌

While it would be the nicest to support everything, this leads to some combinatorial explosion in the algorithms. Moreover, the user interface gets more and more complicated.

Therefore most of the cases will remain missing until sufficient demand.