Module check 

The hand-written format checks the rules are built on.

Laravel leans on PCRE for email, url, uuid and friends. Rustlavel has no regex engine and does not want one, so each shape is a small function here instead. They are deliberately pragmatic, not RFC-exhaustive: the job is to reject the typos a user actually makes in a form, not to accept every address RFC 5322 permits. Each function documents where it draws that line.

Functions

is_alpha

Letters only. Unicode-aware, like Laravel’s default: Ada and Zoë both pass.

is_alpha_dash

Letters, digits, dashes and underscores — the shape of a URL slug.

is_alpha_num

Letters and digits only.

is_date

A calendar date in YYYY-MM-DD, the format an <input type="date"> sends.

is_email

A practical email shape: local@domain, one @, a domain with a real TLD.

is_url

A URL with an explicit scheme and a non-empty host: https://example.com/x.

is_uuid

The 8-4-4-4-12 hex shape of a UUID.