json (js, cli)

json is loads and dumps. Declare it with edge add json and import it by bare name. To pin a different version, point the edge.json entry at another URL, see Modules.

loads accepts the object_hook, object_pairs_hook, parse_float, parse_int, and parse_constant callables. dumps accepts indent, sort_keys, ensure_ascii, check_circular, allow_nan, skipkeys, default, separators, and cls. Parse failures raise ValueError, nesting deeper than 1000 levels raises RuntimeError, and a non-serializable value raises TypeError unless default handles it. Integers cross as 128-bit values, so loads accepts numbers beyond 64 bits. Non-finite floats map to NaN, Infinity, and -Infinity on both sides, and integer-valued floats dump with a trailing .0 so a round-trip preserves the type.

from json import dumps, loads

data = loads('{"name":"ada","tags":["math","cs"]}')
print(data["name"])
print(dumps({"k": [1, 2, 3], "ok": True}))

cmd + enter

ada
{"k":[1,2,3],"ok":true}

Output

indent and sort_keys shape the output:

from json import dumps

print(dumps({"b": 1, "a": [True, None]}, indent=2, sort_keys=True))

cmd + enter

{
  "a": [
    true,
    null
  ],
  "b": 1
}

Output

A round-trip preserves types, even past 64 bits:

from json import dumps, loads

big = 2 ** 100
print(loads(dumps(big)) == big)
print(dumps(3.0))
print(loads(dumps(3.0)))

cmd + enter

True
3.0
3.0

Output

Failures raise ordinary exceptions you can catch:

from json import dumps, loads

try:
    loads("{nope")
except ValueError as e:
    print("parse failed:", e)

def helper():
    pass

try:
    dumps({"fn": helper})
except TypeError as e:
    print("dump failed:", e)

cmd + enter

parse failed: unknown literal at byte 1
dump failed: 'function' is not JSON-serializable

Output