diff --git a/docs/interpolation/common.rst b/docs/interpolation/common.rst
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+Common
+======
+
+env
+---
+
+.. js:function:: env(key)
+
+   :param string key: The environment key to get
+   :return: The value of the environment variable, or "" if it doesn't exist
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   env("FOO") // foo
+
+length
+------
+
+.. js:function:: length(object)
+
+   :param string/list/map object: The object to return the length of
+   :return: The length of the object.
+            If object is a string, it is the number of characters.
+            If object is a list, it is the number of items in the list.
+            If object is a map, it is the number of keys in the map.
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   length("hello") // 5
+   length(["foo", "bar"]) // 2
+   length({"foo": "bar"}) // 1
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diff --git a/docs/interpolation/maps.rst b/docs/interpolation/maps.rst
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+Maps
+====
+
+has
+---
+
+.. js:function:: has(map, key)
+
+   :param map map: The map to perform the lookup on
+   :param string key: The key to look for
+   :return: A bool as to whether or not the key exists
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   has({"foo": "bar"}, "foo") // true
+
+map
+---
+
+.. js:function:: map(key, value, ...)
+
+   :param string key: The key for the key/value pair
+   :param any value: The value for the key/value/pair
+   :return: A map object consisting of the provided key/value pairs
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   map("foo", "bar") // {"foo": "bar"}
+   map("foo", list(1, 2, 3), "bar", list(3, 2, 1)) // {"foo": [1, 2, 3], "bar": [3, 2, 1]}
+
+keys
+----
+
+.. js:function:: keys(map)
+
+   :param map map: The map to extract keys
+   :return: The list of keys from the map
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   keys(map("foo", "bar")) // ["foo"]
+
+merge
+-----
+
+.. js:function:: merge(map1, ...)
+
+   :param map map1:  One or many maps to merge
+   :return: The result of the merge
+
+Example
+^^^^^^^
+
+.. code-block:: guess
+
+   merge(map("foo", "bar"), map("foo", "bar2", "hello", "there")) // {"foo": "bar2", "hello": "there"}
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