>> Just like "mostly secure," "mostly pure" is wishful thinking. The slightest implicit imperative effect erases all the benefits of purity, just as a single ba

>> Just like "mostly secure," "mostly pure" is wishful thinking. The slightest implicit imperative effect erases all the benefits of purity, just as a single bacterium can infect a sterile wound. > Taking the analogy to its logical conclusion, the only healthy diet is a 100% strict diet allowing no impure substances. Very few people can actually live this way and it's questionable whether anyone should. I have a simpler one: "Mostly const". Mostly-const gives you the best of both worlds: you get the benefits of knowing it stays the same, and the practicaliy of being able to change it (despite those const zealots who demand that you shouldn't change const variables) Erik Meijer is pushing back on language designers that push self-contradictory feature: "It's OO AND functional! Best of both worlds."