A macro or FEXPR may never evaluate an operand at all. They simply receive the unevaluated forms and decide what to do with them, with explicit evaluation being

A macro or FEXPR may never evaluate an operand at all. They simply receive the unevaluated forms and decide what to do with them, with explicit evaluation being just one option which can be performed on the operand. Delayed (lazy) evaluation merely prevents an operand being evaluated at the time of call and until you want to read its reduced value, after which it is automatically evaluated.