Clojure library learning, concrete examples section.

clj/README.md

        whole documentation and have spend too much time tracking weird
        errors down that were all fixed by changing one place in the
        code
    * learning new libraries without sufficient docs/tutorials (e.g.
        what are the arguments to this function, what does this map mean;
        maybe clojure wants me to think differently)
    * the jvm overhead is bad for my little computer (too slow, too much
      memory consumed)
## Hickups
Some examples for the quibbles.
* `(if (= something something-undefined) true-expr false-expr)` not
    throwing an exeption for `something-undefined` being not defined