Separating arguments to a function, in locales with comma as decimal marker

Question

In locales, e.g. French, with comma as decimal indicator (where "5,2" means five and two-tenths), how do users separate function arguments from each other?

For example, in many programming/scripting languages, I could specify MAX(1.5, X) in a EN-US locale. How do you avoid the ambiguity between the comma as decimal indicator, and as argument separator?

In particular, I'm interested in how software that's perceived as user-friendly in the foreign locale does it. Obviously, it's a no-brainer to say, "thou shalt use decimal POINTs", but that's not particularly "friendly".