I'm a bit puzzled by whether Fennel is trying to make "different things look different" as they claim, or not. On the one hand, Fennel separates Lua's multipurpose "for" into "for" (for numeric ranges) and "each" (for iterators). On the other hand... Don't macros and function calls, two rather different things with different powers, look identical in Fennel?

On the "Values" page, they also mention a macro that alters the lexical scope somehow. This macro is now deprecated, but its mere existence implies that such a macro can be expressed in Fennel -- that is, that it's possible to write Fennel code that causes what looks like an ordinary function call to do surprising things to the program state.

As they rightly mention (on either this page or the "Values of Fennel" page), the advantage of constraining a language is that you can more easily tell what a program is doing (and not doing) at a glance. But this seems to be undone by giving a pass to (unhygienic?) macros.