Repl namespace issue about clojure-koans

[trptcolin]

Yeah, I can see why that's confusing. Here's a short-term fix for you:

koan-engine.runner=> (clojure.string/join '(1 2 3))
"123"

...or...

koan-engine.runner=> (require '[clojure.string :as string])
nil
koan-engine.runner=> (string/join '(1 2 3))
"123"

See https://8thlight.com/blog/colin-jones/2010/12/05/clojure-libs-and-namespaces-require-use-import-and-ns.html for more detail.

I think there are probably improvements we can make to the koans in order to make it clearer what's going on with namespaces, so I'll leave this open as a reminder (and in case anyone wants to tackle it!)