All functions that take distributions should take numbers.

[Hazelfire]

This is an interesting question, but I think functions like mean should take a number and return the same number. If a number is put instead of distribution, it should be considered a degenerate distribution for that one value.

This would make my code about sensitivity / value of information analysis a bit simpler

[Hazelfire]

I think the collorary should also be true, any function that takes a number should take a distribution. For instance, mean(list[number]) exists but I think mean(list[distribution]) should exist too. This however has interesting implications with distribution constructors.