HashiCorp Configuration Language (HCL) supports user-defined functions.

This is false because HCL's specification explicitly excludes user-defined function support; users are limited to the curated set of built-in functions provided by the Terraform runtime.

HashiCorp Configuration Language intentionally omits support for user-defined functions to keep configurations declarative, readable, and free from hidden side effects. All callable functions such as 'merge()', 'lookup()', and 'toset()' are built into the Terraform runtime and cannot be extended or overridden by users. This design constraint prevents configurations from becoming imperative scripts and maintains the language's predictability.