What determines the entropy of a program's source code?
This is a classical question in the foundations of Kolmogorov complexity: does the programming language matter for the sake of defining minimal description length? It depends on your model, but in general the answer is "no" or "almost no".

Suppose that $P_1,P_2$ are two Turing complete programming languages. In particular, in $P_1$ you can write an interpreter $I$ for $P_2$. Therefore any program $\pi$ written in $P_2$ can be converted in $P_1$ by pasting together $I$ and $\pi$. What is the length of the combined program? In any reasonable programming language, it is $O(|\pi|)$, and so different programming languages only have at most a constant multiplicative advantage over each other. If we are more stringent in our requirements on the programming languages, the answer should be $|\pi| + O(1)$, which is what happens in Kolmogorov complexity. In this case different programming languages only have at most a constant additive advantage over each other.

The idea behind $\pi + O(1)$ is that you should be able to concatenate the code for $I$ with $\pi$. But in practice this is not quite possible. Suppose for example that $P_1$ is $C$. We need to write $\pi$ as a string. If the character set of $\pi$ includes backslash or double quotes, then we will need to escape these, which could result in a multiplicative blow-up. Still, we get a $C$ program whose length is $O(|\pi|)$. If we are careful in our definitions then we can prevent this &mdash; check any introductory text on Kolmogorov complexity for the details.