Hoon is mainly built on a fixed set of hardwired, built-in macros. This is how I can be so confident about not needing anything like gensyms (what eliminates gensyms is having a subject which is navigated geometrically, not symbolically).

The advantage of fixing the set of hardwired macros is that, when reading code, everyone knows exactly what every line is doing, without having to indirect through the local macro environment. Macros are the first step toward a DSL.

DSLs are always and everywhere a bad idea. They may make code slightly cleaner or better-looking. In exchange, they add a level of indirection to the task of trying to understand it. This is the source of the nickname "write-only code," a common failure mode in FP. Write-only code can also be created by extravagant and pointless use of higher-order or non-strict programming, both of which complicate the task of reading code.

For instance, Hoon has a rune (keyword or digraph) for a 2-tuple, a 3-tuple, a 4-tuple, but not for a 5-tuple or up. Why? The 4-tuple cons pulled its weight, the 5-tuple didn't. For every special form you add to Hoon's fixed, limited set, you're imposing a cost on anyone who has to learn Hoon.

I hope you can see the UI advantage to functional programming in an environment of controlled evaluation complexity. IMHO, too much of FP is a world in which every program is its own language.

Which one is right? Actually, I feel it's possible that the only real language is K, and the rest of us are just phonies.