| Lisps (like Clojure) treat code as data (lists), so you write: `(if x (y) (z))` instead of Python’s `y() if x else z()`. So the code is more concise, but does less to walk a novice through it. This gains a huge advantage, which allows even more concision: all code is data, so its easy to transform the code. In Clojure if you want to add support for unless, a thing like if, but evaluating the opposite way you could do this: `(defmacro unless [p a b] `(if (not ~p) ~a ~b))`. Obviously if you wanted to do the same thing in Python you would in practice do `z() if x else y()`. However, you would do it that way because Python isn't as powerful a language. To actually do the same thing in Python you would need to... 1. Add __future__ support. 2. Update the Python language grammar. 3. Add a new AST type. 4. Add a new pass stage to the compiler. 5. Add a python library to integrate with this so you could use it. Then you could do something like: from __future__ import macros
defmacro unless(pred, then: block, else_: block = []):
return q[
if not u(pred):
u*(then)
else:
u*(else_)
]
So in the trivial case its just hundreds of lines harder plus requires massive coordination with other people to accomplish the same feat.This sort of, wow, it takes hundreds or thousands of lines more to accomplish the same thing outside of Lisp as it does to accomplish it within Lisp shows up quite often; consider something like chaining. People write entire libraries to handle function chaining nicely. `a.b().c().d().map(f).map(g)`. Very pretty. Hundreds of lines to enable it, maybe thousands, because it does not come by default in the language. But in Lisp? In Clojure? Just change the languages usual rules, threading operator and now chaining is omnipresent: `(->> a b c d e (map f) (map g))`. Same code, no need to write wrapper libraries to enable it. |