I always read it with an implied "let" in front, so it has always sounded completely natural. It's also ergonomic to type, easy to read and while you can confus

I always read it with an implied "let" in front, so it has always sounded completely natural. It's also ergonomic to type, easy to read and while you can confuse := and = on account of : being a small glyph even in monospace fonts - you can mistake it for empty space if you're just skimming, == and = are harder to confuse since one is twice as long as the other.