{% set foo = [1, {"foo": "bar"}] %}
+.. tip::
+
+ Using double-quoted or single-quoted strings has no impact on performance
+ but string interpolation is only supported in double-quoted strings.
+
Math
~~~~
String interpolation was added in Twig 1.5.
String interpolation (`#{expression}`) allows any valid expression to appear
-within a string. The result of evaluating that expression is inserted into the
-string:
+within a *double-quoted string*. The result of evaluating that expression is
+inserted into the string:
.. code-block:: jinja