rontolisp:json-stringify

(rontolisp:json-stringify value)

Serializes a Lisp value into a JSON document string, modeled on JavaScript's JSON.stringify. Both object representations produced by rontolisp:json-parse serialize back to JSON objects: a property list whose keys are keywords, and a hash table (keys may be strings, symbols, keywords or numbers).

Value mapping

Lisp	JSON
`nil`	`null`
`t`	`true`
integer, float	number
ratio	number (converted with `float`)
string	string (quote, backslash and control characters are escaped)
keyword, symbol, character	string (a keyword drops its leading colon)
non-empty list of alternating keyword/value pairs	object
any other list	array
hash table	object (iteration order is unspecified)

Anything else (functions, streams, promises, arrays) signals an error.

A value parsed from JSON round-trips structurally:

Limitations

A list is serialized as an object exactly when it looks like a keyword property list ((:a 1 :b 2)); a genuine array whose elements alternate keywords and values is indistinguishable and becomes an object.
nil always serializes as null — there is no way to produce an empty array [] or (from a plist) an empty object {}; build an empty hash table for the latter.
Hash-table key order in the output is backend-specific (unspecified), like maphash.
Non-ASCII characters are emitted verbatim (never \uXXXX-escaped), which is valid JSON.
On the WASM backends a float with magnitude 2³¹ or larger cannot be serialized (the float formatter traps); see the WASM guide.

Backend support

Works on every backend and in every WASM mode (Preview 1 included), like rontolisp:json-parse: the serializer is written in rontolisp itself and is compiled into the program when used.