github.com/hugorut/terraform@v1.1.3/website/docs/language/functions/index.mdx (about)

     1  ---
     2  page_title: Functions - Configuration Language
     3  description: >-
     4    An introduction to the built-in functions that you can use to transform and
     5    combine values in expressions.
     6  ---
     7  
     8  # Built-in Functions
     9  
    10  > **Hands-on:** Try the [Perform Dynamic Operations with Functions](https://learn.hashicorp.com/tutorials/terraform/functions?in=terraform/configuration-language&utm_source=WEBSITE&utm_medium=WEB_IO&utm_offer=ARTICLE_PAGE&utm_content=DOCS) tutorial on HashiCorp Learn.
    11  
    12  The Terraform language includes a number of built-in functions that you can
    13  call from within expressions to transform and combine values. The general
    14  syntax for function calls is a function name followed by comma-separated
    15  arguments in parentheses:
    16  
    17  ```hcl
    18  max(5, 12, 9)
    19  ```
    20  
    21  For more details on syntax, see
    22  [_Function Calls_](/language/expressions/function-calls)
    23  in the Expressions section.
    24  
    25  The Terraform language does not support user-defined functions, and so only
    26  the functions built in to the language are available for use. The navigation
    27  for this section includes a list of all of the available built-in functions.
    28  
    29  You can experiment with the behavior of Terraform's built-in functions from
    30  the Terraform expression console, by running
    31  [the `terraform console` command](/cli/commands/console):
    32  
    33  ```
    34  > max(5, 12, 9)
    35  12
    36  ```
    37  
    38  The examples in the documentation for each function use console output to
    39  illustrate the result of calling the function with different parameters.