An Intuition for Lisp Syntax
Every lisp hacker I ever met, myself included, thought that all those brackets in Lisp were off-putting and weird. At first, of course. Soon after we all came to the same epiphany: lisp’s power lies in those brackets! In this essay, we’ll go on a journey to that epiphany.
But…your spidey sense may already be tingling. What if the user was malicious and managed to send us an instruction like this:
Uh oh…our cookie would get sent to iwillp3wn.com, and the malicious user would indeed pwn us. We can’t use eval; it’s too dangerous.
Well, we could represent those instructions as JSON. We can map each JSON instruction to a special function, and that way we can control what runs. Here’s one way we can represent it:
Well, since every instruction has a functionName, and an args, we don’t really need to spell that out. We could write it like this:
Nice! We changed our object in favor of an array. To handle that, all we need is a rule: the first part of our instruction is the function name, and the rest are arguments. If we wrote that down, here’s how our onMessage would look:
