This would maybe be possible in C if the "functional" keyword was added (as suggested in the letter), and the compiler can be sure that the function doesn't use anything apart from its (const) arguments to generate a return value.

Then it also would need to make sure that those parameters can't change between different calls within the same function.

This wouldn't be feasible in the example above, since that function explicitly depends on outside variables. If you were to supply both `health` and `alive` as arguments, you could pretty much write the check yourself from the beginning.

Of course, there are many bigger checks that could benefit from this, but still, you (or the compiler) have to make sure that all functions are pure, that no arguments can change etc etc. I imagine that this could make compile times quite slow (and also complicated to write the compiler itself).