> For the complete documentation index, see [llms.txt](https://nelson-9.gitbook.io/nelson/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nelson-9.gitbook.io/nelson/markdown/en/interpreter.md).

# Interpreter functions

The Interpreter Functions module provides the core language constructs and control mechanisms that define the execution flow in Nelson.

It includes essential elements such as loops, conditional branching, error handling, and function declarations.

The module also offers tools for parsing code, working with keywords, and managing recursion limits.

Together, these features establish the fundamental syntax and semantics of the Nelson language, enabling users to write structured, dynamic, and reliable programs.

## Functions

* [abort](/nelson/markdown/en/interpreter/abort.md) - stop evaluation.
* [return](/nelson/markdown/en/interpreter/abort.md) - stop evaluation.
* [arguments](/nelson/markdown/en/interpreter/arguments.md) - function argument validation block.
* [break](/nelson/markdown/en/interpreter/break.md) - exit evaluation loop.
* [comments](/nelson/markdown/en/interpreter/comments.md) - Add comments to Nelson code.
* [continue](/nelson/markdown/en/interpreter/continue.md) - continue evaluation in loop.
* [for](/nelson/markdown/en/interpreter/for.md) - for loop.
* [parfor](/nelson/markdown/en/interpreter/for.md) - for loop.
* [function](/nelson/markdown/en/interpreter/function.md) - function declaration.
* [endfunction](/nelson/markdown/en/interpreter/function.md) - function declaration.
* [if](/nelson/markdown/en/interpreter/if.md) - conditional statement.
* [tilde](/nelson/markdown/en/interpreter/ignore_outputs_function.md) - Ignore outputs function.
* [iskeyword](/nelson/markdown/en/interpreter/iskeyword.md) - Returns all Nelson keywords.
* [keyboard](/nelson/markdown/en/interpreter/keyboard.md) - Stops script execution and enter in debug mode.
* [max\_recursion\_depth](/nelson/markdown/en/interpreter/max_recursion_depth.md) - Internal limit on the number of times a function may be called recursively.
* [name=value](/nelson/markdown/en/interpreter/name_value_syntax.md) - Name=value syntax for name-value arguments.
* [numeric types](/nelson/markdown/en/interpreter/numeric_types.md) - About integer and floating-point data.
* [onCleanup](/nelson/markdown/en/interpreter/oncleanup.md) - Cleanup tasks upon function completion
* [parsefile](/nelson/markdown/en/interpreter/parsefile.md) - Parse a Nelson file.
* [parsestring](/nelson/markdown/en/interpreter/parsestring.md) - Parse a string.
* [switch](/nelson/markdown/en/interpreter/switch.md) - switch statement.
* [try](/nelson/markdown/en/interpreter/try.md) - try/catch statement.
* [catch](/nelson/markdown/en/interpreter/try.md) - try/catch statement.
* [while](/nelson/markdown/en/interpreter/while.md) - while loop.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://nelson-9.gitbook.io/nelson/markdown/en/interpreter.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.