I think at the end of the day, the question is whether a compiler for this type of language could efficiently handle a function like distinct-sorted:

   > (distinct-sorted '(foo bar foo baz))
   (bar baz foo)

This is a function that usually requires efficient hash tables and arrays to be performant, a hash table for detecting the duplicates, an array for efficient sorting. However, both the hash map and array could theoretically be "optimized away", since they are not exposed as part of the output.

A language like Bel that does not have native hash maps or arrays and instead uses association lists would have to rely entirely on the compiler to find and perform these optimizations to be considered a usable tool.