JSON Pointer evaluation.

This module extends the Data.Aeson.Zipper interface with an additional function, descend, that allows for moving to any location inside a JSON document in one step. The "address" of the target location is specified using JSON Pointer [RFC 6901].

Decode a JSON document and anchor it to the top-level zipper context:

>>> let tloc = decode "{\"root\": {\"foo\": [1,2], \"bar\": true}}" >>= anchor

Move to the zeroth entry of the foo array using JSON Pointer:

>>> let foo0 = tloc >>= descend "/root/foo/0"

The value in that location is number 1:

>>> getValue foo0
Number 1.0

And we change this entry to the string hi and return to the top:

>>> let tloc' = foo0 >>= replace (String "hi") >>= top

Now we can check the modified JSON document:

>>> encode $ getValue tloc'
"{\"root\":{\"foo\":[\"hi\",2],\"bar\":true}}"