There’s a pattern called the call-with pattern that gives you this dynamic behavior of blocks. But, in many cases, Ruby and JS use this sort of dynamic “macro”

There’s a pattern called the call-with pattern that gives you this dynamic behavior of blocks. But, in many cases, Ruby and JS use this sort of dynamic “macro” where there’s not really a benefit to dynamic evaluation: with a macro you can always wrap the block of code with an anonymous function at macro-expansion time and opt-in to dynamic evaluation; Ruby blocks (and arrow-function DSLs in JS) force you to pay the overhead of dynamic evaluation even when you only need compile-time information