# Expression functions

Expression functions are used to help build expressions defined in some nodes, such as conditional checks or variable value assignments.

They are grouped into several packages, based on their purpose.

## Packages

* [pdk.util.Any](expression-functions/pdk.util.any) - contains most basic functions applicable to any variable.
* [pdk.util.Array](expression-functions/pdk.util.array) - contains functions to work with arrays.
* [pdk.util.Blockchain](expression-functions/pdk.util.blockchain) - contains functions to manage and manipulate blockchain data.
* [pdk.util.Cast](expression-functions/pdk.util.cast) - contains functions to convert variable values from one data type to another.
* [pdk.util.Codec](expression-functions/pdk.util.codec) - contains functions to transform variable values to/from specialized encoded formats.
* [pdk.util.Crypto](expression-functions/pdk.util.crypto) - contains functions to encrypt/decrypt data.
* [pdk.util.Date](expression-functions/pdk.util.date) - contains functions to work with dates and timestamps.
* [pdk.util.File ](expression-functions/pdk.util.file)- contains functions to work with Files.
* [pdk.util.Json](expression-functions/pdk.util.json) - contains functions to work with JSON-formatted data structures.
* [pdk.util.JWT](expression-functions/pdk.util.jwt) - contains functions to control application security with JSON web tokens.
* [pdk.util.Map](expression-functions/pdk.util.map) - contains functions to work with maps.
* [pdk.util.Math](expression-functions/pdk.util.math) - contains functions to perform mathematical operations.
* [pdk.util.String](expression-functions/pdk.util.string) - contains functions to work with strings.
* [pdk.util.Util ](expression-functions/pdk.util.util)- contains some other utility functions.
