The Root Object

The root object is the object that is passed in to each patch file. When a patch is being applied to a target file the root will correspond to the target files contents. When a patch is being imported as a library the root will be an empty object that will be given to the importer as a variable.

The $

The $ syntax is used to get the root object. It can be used like any expression, but it isn't a reference. It can be used as a function parameter, but it can't be assigned to.

val root = $; # You can store the root object in a variable

function a() {
    return $; # You can return the root object from a function
}

apply ($) { # You can use the root object as the root object (don't do this)
}

Implicit Property Access

When accessing a property of the root object you can omit the dot. This changes nothing functionally, but makes your code a bit more readable.

$a; # This is the same as $.a

Apply Statements

Apply statements allow you to execute code with a different root. This is useful if you have a large piece of code that has to act on a specific part of the json.

apply (a) {
    $b; # This will return the value of a.b
}