_index.md

---

aliases:
- ../configuration-language/expressions/
title: Expressions
weight: 400

---

Expressions

Expressions represent or compute values that can be assigned to attributes within a configuration.

Basic expressions are literal values, like "Hello, world!" or true. Expressions may also do things like [refer to values][] exported by components, perform arithmetic, or [call functions][].

Expressions can be used when configuring any component. As all component arguments have an underlying [type][], River will type-check expressions before assigning the result to an attribute.

[refer to values]: {{< relref "./referencing_exports.md" >}} [call functions]: {{< relref "./function_calls.md" >}} [type]: {{< relref "./types_and_values.md" >}}