JSONTransform

JSONTransform is a declarative language for transforming JSON objects based on pattern matching, destructuring, and selector languages.

A JSONTransform document is a kind of template that uses pattern matching to populate values. When applying a JSONTransform to a JSON object, Strings in the transform document that start with = are interpreted as JSONSelect selectors, and replaced with the selected results from the object. There is also a expression language, and language bindings to allow functions from the host language to be called.

When matching the object

{
  "name": {
    "first": "Marty",
    "fast": "Gentillon"
  },
  "address": {
    "street": "00000 Fake St.",
    "city": "Seattle",
    "state": "WA",
    "zip": 99999
  }
}

Against the JSONTransform

{
  "Name": ["@join", " ", "=.name.first", "=.name.last"],
  "Address": ["@join", "\n",
    "=address.Street",
    ["@join", " ", "=.address.city", "=.address.state", "=.address.zip"]]
}

will produce

{
  "Name": "Marty Gentillon",
  "Address": "0000 Fake St.\nSeattle WA 99999"
}

Principles:

1. the output should look like the input
2. The JSONTransform document is a JSON document

strings are indicated with the / sigil, which will be removed from the front. Additionally, strings with no recognized, or reserved sigil will be treated as strings as is.

Language callbacks are indicated with the % sigil at the beginning of an array. They may be implemented various ways.

Input

{
  "subject": "test",
  "body": "blah blah",
  "bad data": "evil"
}

{"@keys": ["subject", "body"]}

or

{"@remove-keys": ["bad data"]}

output

{
  "subject": "test",
  "body": "evil"
}

Input

[["key1", "value1"],
["key2", "value2"]]

["@assoc", ":root"]

{
  "key1": "value1",
  "key2": "value2"
}

operations: [@join, on, *values] [@assoc, list-to-assoc, key-selector default :first-child, value-selector default :nth-child(2)] <# needs a better name #> [@deassoc, map-to-deassoc, value-template default ["@key", "@value"]] [@transform-in, document-to-transform, selector-to-apply-sub-transform-on, sub-tranform] [@concat, *collections-to-join] [@group-by, collection-to-group, key-selector] [@transform, document-to-transform, sub-transform] [@union, *documents-to-unionize] <# how to handle collisions? choose first? #> ?[@select] ?[@reject] ? comparison, tests, and math operators

special keys: @keys @remove-keys @as @remaining

variables? maybe using _, or just using @ syntax