Once the ‘programming bit’ is flipped in someone’s brain, I think metasyntactic variables like foo and bar become very instinctive and easy to reason about. You

Once the ‘programming bit’ is flipped in someone’s brain, I think metasyntactic variables like foo and bar become very instinctive and easy to reason about. You have activated the part of your brain that visualizes things as abstractions with placeholders. The problem is when foo and bar are used in material aimed at beginning programmers who are still developing that instinct and who haven’t yet got that bit set.