As a frequent user of each of these languages this appears quite cool

The thing putting me off is both PHP and Clojure have mature/maturing tooling that I suspect would be unusable here

On the PHP side there's LSP servers, xdebug 3, PHPStorm (the only reliable client for xdebug I've found) xhprof, phan etc

On the Clojure side there's Cider, Cursive, Structural editing tools, Clj-kondo, Clojure-lsp

I love dynamic languages but I wouldn't use a new one without a few good static analysers and deep debuggers