For one, the service that performs the vast majority of airfare searches -- formerly ITA Software, now Google Flights.<p>Having spent time at the MIT AI Lab and having co-founded a company whose principal product was a Lisp&#x2F;C hybrid, I think the challenge with mainstream adoption of both Lisp-like and functional languages is the syntax. There&#x27;s an element of &quot;don&#x27;t use a programming language that&#x27;s hard to hire for&quot; but I think that&#x27;s secondary as it never bothered us or posed a real problem.<p>Naughty Dog&#x27;s Crash Bandicoot games (which I also worked on) used Lisp for all the character control logic.