@assertions:charset!

Whether every byte of the string return of a call is in a character class, checked on-chain — only-lowercase is @charset!(call a-z).

Returns: bool

Syntax

@assertions:charset!(call class)

Arguments

Name	Type	Description
call	address	A :: call expression (or chain) returning a string
class	string	Allowed characters and ranges, e.g. a-z0-9- (a leading or trailing dash is the literal -)

Examples

load assertions

set $token 0x44fA8E6f47987339850636F88629646662444217

# The symbol contains only lowercase letters
assertions:assert @charset!($token::{symbol()(string)} "a-z") == true

# An ENS-label-ish name: lowercase, digits and dashes
assertions:assert @charset!($token::{name()(string)} "a-z0-9-") == true

Notes

• The class is characters and x-y ranges; a leading or trailing dash is the literal -. It compiles to a 256-bit byte bitmap at build time — the on-chain check is one bit test per byte.
• Byte-level: multi-byte UTF-8 characters (every byte ≥ 0x80) fail any ASCII-only class, so a-z really means lowercase ASCII.
• The empty string passes every class — pair with @len!(call) > 0 when the value must also be non-empty.
• Boolean-valued: usable bare, compared with == true / == false, or nested inside @bool!(...) logic.

See Also

• assertions:assert, @assertions:includes!, @assertions:len!