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by anamax 6288 days ago
JSON is a subset of s-expressions. (Yes, s-expressions provide explicit and compact representations for mappings. They also handle other kinds of objects.)

The other difference is that there are JSON parsers and generators for more languages and they're not programmable.
1 comments
smallpaul 6288 days ago
Don't tell me. Show me. Please translate the example into s-expressions.
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anamax 6288 days ago
I'm confused why you don't see this as obvious. (There are several possible ways to represent mappings. I picked one that was close to something that you're happy with.)

{ ("x" ( { ("y" "a") ("z" 23) ("q" ( 54 32 45 )) } )) ("r" 43) }

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time_management 6287 days ago
Clojure uses {} for maps, #{} for sets, and [] for vectors, and vectors are used in function definitions, let statements, etc. This slight decrease in regularity makes a lot of functionality more visible. For example:

SBCL:

(defun f (x y) (let ((z (gethash x :a))) (+ z y))

Clojure

(defn f [x y] (let [z (get x :a)] (+ x y)))

Having syntax for maps is a huge win. Like ML's pattern matching, it's one of those things that changes your coding style entirely for the better, in a way that you wouldn't predict just by looking at the feature.

The only think I miss from CL when I work in Clojure is keyword arguments to functions. There, the Clojure way is a bit worse:

(defun f (x &key y z) (list x y z)) (f 2 :z 3) => (2 nil 3)

(defn f [x {y :y z :z}] (list x y z)) (f 2 {:z 3}) => (2 nil 3)

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anamax 6286 days ago
> (defun f (x y) (let ((z (gethash x :a))) (+ z y))

vs

> (defn f [x y] (let [z (get x :a)] (+ x y)))

The CL defn of f is a function that is called with two arguments. That function is called like "(f a b)" If the Clojure definition is comparable, that is, the call looks like "(f a b)", why are []s used in the definition and the let?

> This slight decrease in regularity makes a lot of functionality more visible.

What functionality? x,y aren't part of a vector and neither is z. (x,y may come from a vector in the caller, but I'll assume that the defn works if they don't, so that shouldn't matter.)

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