Complete type system: DECIMAL, full temporal, BOOLEAN, three-valued logic

[siyul-park]

Summary

Some SQL types lack a faithful representation and NULL handling is simplified.

Scope

• Exact DECIMAL/NUMERIC (no float rounding)
• Full DATE / TIME / TIMESTAMP / DATETIME with timezone
• BOOLEAN as a distinct type
• Complete three-valued logic for AND/OR/NOT and comparisons
• Implicit/explicit type coercion rules matching standard SQL

Acceptance

Arithmetic, comparison, and NULL behavior match standard SQL for every type.

Notes

Extend value/ and the runtime boxing layer. Boxed carries no SQL type tag, so non-native types currently use a heap cell; a tagged representation may be needed.