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Being able to use the same syntax for code and data is no small thing. This aspect alone puts it above JSON. That, and for most LISPS, S-expressions have a broader vocabulary than JSON (symbols, complex numbers, etc.).

JSON also has hash tables (which they confusingly call “objects”), which sexps do not. One may argue that one is or isn’t slightly better than the other, but the point was that they are very close.

S-expressions can express whatever the LISP can express (like Clojure's built-in hash table syntax), or the s-exp could just pass a lambda to generate the data on-the-fly at the next step, and since the lambda itself is a list, the receiver has an easy built-in facility for inspecting/altering/extending passed-in code.

JSON is just arrays, objects, bools, numbers, strings, and null.

How are they "close"?

If you have to run “eval” on it, it’s not an s-expression. If the “eval” is implied, what you are describing is serialization of data, not actual data.

You could do what you describe with JSON too – it’s just encoding and decoding. Would you therefore be able to claim that JSON is capable of transmitting, say, tabular data? Of course not.

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