I do sometimes write the constant first, because I want to reduce the amount of punctuation. If you write:

    foo $x, $y == 4
[download]

then foo isn't called with arguments $x and $y. You'd need to write that as:

    foo ($x, $y) == 4
[download]

Or

    4 == foo $x, $y
[download]

And since == is a symmetric operation (assuming it's not overloaded), I don't feel strongly for the "topic first" argument. But I can see your point.

Abigail