Variants

What Are Variants

A variant domain stores key value domain pair fields. However, unlike a record, a variant literal can only use one of these fields at once. This field is referred to as active.

Variants contain a list of fields, with domains, which they can take. They are defined for both GroundDomain and UnresolvedDomain, and stored as Variant(Vec<FieldEntry>).

The result of a variant is a single field value. As such the AbstractLiteral for variants is defined as Variant(Moo<FieldValue<T>>). This AbstractLiteral type means variants can be represented explicitly.

Operators

There is one special operator which is defined on only variants.

• Active(v, f) - Returns whether field f is currently the field active in variant v.

Variants can also be indexed, which makes use of Conjure-Oxide’s UnsafeIndex and SafeIndex.

Note on Implementation

Currently variants are defined within the AST of Conjure-Oxide and can be parsed with the ‘legacy’ parser. However, there is no support as of Apr-2026 for rewriting rules or solving.