> For the complete documentation index, see [llms.txt](https://docs.hylo-lang.org/hylo-ir/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hylo-lang.org/hylo-ir/concepts/operands.md).

# Operands

Instructions in Val IR may accept operands embodying values to be operated upon. There exists 5 types of operands:

* **Type references**: A type reference denotes a lowered type definition.
* **Basic block references**: A basic block reference denotes a basic block.
* **Constants**: A constant is a value that is computed at compile time and immutable at runtime.
* **Basic block arguments**: A basic block argument denotes the value passed to a basic block when control flow entered to its entry point.
* **Instruction results**: An instruction result denotes the one of the values produced by the evaluation of an instruction.

{% hint style="info" %}
A thin function reference is a constant because it is immutable. Similarly, the memory location of a global binding's storage is a constant.
{% endhint %}

Each basic block argument and instruction result is assigned to a unique local register in the function. The value of a register 

## Uses

An instruction `i` is said to be a *user* of an operand `o` if `o` is argument of `i`. Each occurence of an operand in one of its users is called a *use*.

Given two uses `u1` and `u2`, `u2` is sequenced after `u1` (or, equivalently, u1 is sequenced before u2) if and only if:

* the user of `u2` is sequenced after the user of `u1`, or
* `u1` and `u2` have the same user and `u1` appears before `u2`.


---

# 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, and the optional `goal` query parameter:

```
GET https://docs.hylo-lang.org/hylo-ir/concepts/operands.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.