Well Clojure is a language designed to be evaluated form by form if for example I wanted to evaluate an if statement in PHP's "REPL" then working out where that statement begins and ends is annoying compared to just sending an if expression in Clojure
In PHP once a function is defined I can't redefine it and then call it again to iteratively build that function
Just because your language has a repl doesn't mean you can get a quick feedback loop from it, in fact the more compile time constructs you have like classes and interfaces the harder it is, particularly if they're sticky with dependencies everywhere
Bret Victor's work I think really illustrates how little respect and investigation we do into feedback loops
In PHP once a function is defined I can't redefine it and then call it again to iteratively build that function
Just because your language has a repl doesn't mean you can get a quick feedback loop from it, in fact the more compile time constructs you have like classes and interfaces the harder it is, particularly if they're sticky with dependencies everywhere
Bret Victor's work I think really illustrates how little respect and investigation we do into feedback loops