It looks like Lisp and Clojure programmers often develop programs directly in the REPL. cf. Clojure Development: IDE or REPL?
My question is, why isn't this approach more common in Ruby, via irb? Is this just a cultural difference, or are there structural (language-specific) reasons why REPL-centric development is more common with Lisps than with languages like Ruby and Python?
Lisp syntax seems to lend itself very nicely for a combined REPL-and-source-file approach. It is much easier to move code snippets around programmatically when the textual limits of each form are clear.