That is pretty cool, and I wish such features were common in regular UNIX shells.

For good measure, this is how you might do the same with jb:

    $ jb Hello=world array:number[]@<(seq 10) object:json@<(date=$(date -Iseconds) jb @date)
    {"Hello":"world","array":[1,2,3,4,5,6,7,8,9,10],"object":{"date":"2024-07-03T19:26:36+00:00"}}

Alternatively, using the :{} object entry syntax:

    jb Hello=world array:number[]@<(seq 10) object:{}=date=$(date -Iseconds)
    {"Hello":"world","array":[1,2,3,4,5,6,7,8,9,10],"object":{"date":"2024-07-03T19:30:26+00:00"}}