Global functions

Rell provides a collection of built-in global functions for common tasks. For complete API documentation, see the Standard Library reference.

Overview

Global functions are available without any namespace prefix and cover:

• Math operations – abs, min, max for integer, big_integer, and decimal types
• Collection checks – empty and exists for nullable values, lists, sets, and maps
• Output – print and log for debugging
• Cryptographic hashes – sha256, keccak256
• Signature verification – verify_signature
• Ethereum operations – eth_ecrecover for public key recovery
• Error handling – require, rell.error, try_call, and try_call_catch, documented under require and error handling

Key functions

• abs – Returns the absolute value of a number
• min, max – Returns the smaller/larger of two values
• empty – Checks if a value is null or an empty collection
• exists – Checks if a value is non-null and non-empty
• print, log – Output to stdout or log
• sha256, keccak256 – Cryptographic hash functions
• verify_signature – Verifies a signature against a message and public key
• try_call, try_call_catch – Catch exceptions; see require and error handling

Using empty and exists in at-expressions

Both empty() and exists() support nested at-expressions, enabling efficient SQL queries:

// Find users with no company in their city
user @* {
    empty(company @* { .city == user.city })
}

// Find users with at least one company in their city
user @* {
    exists(company @* { .city == user.city })
}

Use @* in nested at-expressions to execute as a single SQL query. Other cardinality operators (@+, @?, @) result in separate queries.