Thanks for all of the examples. It’s clear that my objection was misguided; it’s my eye and intuitions that aren’t properly tuned to common syntactic patterns for lambda expressions.
(In recent years I’ve been mostly using Clojure/Clojurescript, OCaml, R, and Netlogo, using Javascript and Java only when I have to do so in order to interface with my preferred languages. As a result, I haven’t had to keep up with the most recent developments. Yet.)