This is documentation for the next version of Agent. For the latest stable release, go to the latest version.

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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.