Import
import { Fx } from "@typed/fx/Fx";Access Fx.Variance through the imported Fx export. Its declaration below describes the member.
Signatures
interface Variance<A, E, R> {
readonly _A: Types.Covariant<A>;
readonly _E: Types.Covariant<E>;
readonly _R: Types.Covariant<R>;
}Why
The phantom fields preserve Fx<A, E, R> relationships through TypeScript’s
structural type system and power channel extraction without runtime sampling.
Ownership and lifetime
Variance markers are type-level metadata and retain no values or resources.
Property: _A
Covariant marker for emitted values.
Property: _A: Why
Preserves the A relationship without retaining an emitted value.
Property: _A: Ownership and lifetime
This phantom field starts no work and owns no resource.
Property: _E
Covariant marker for typed failures.
Property: _E: Why
Preserves the E relationship without manufacturing a failure.
Property: _E: Ownership and lifetime
This phantom field starts no work and owns no resource.
Property: _R
Covariant marker for required services.
Property: _R: Why
Preserves the R relationship without reading an Effect context.
Property: _R: Ownership and lifetime
This phantom field starts no work and owns no resource.
Examples
import type { Fx } from "@typed/fx/Fx"
type NumberFxVariance = Fx.Variance<number, never, never>Other public imports
These import paths expose the same declaration. Each page retains its own public name and signature.