For me, coming from java, macros and closures were the two concepts that were completely alien and made a huge difference. Java provides a lot of structure (pac

For me, coming from java, macros and closures were the two concepts that were completely alien and made a huge difference. Java provides a lot of structure (packages, classes, interfaces) that result in a lot of reassuring boilerplate code. If you're using lisp for conciseness, there is no boilerplate to comfort you, to signal where you are and what you should be doing at this point in the code.