General schemes
Arbitrary schemes over a commutative base ring $\mathbb k$ with unit are instances of the abstract type
Scheme — TypeScheme{BaseRingType<:Ring}A scheme over a ring $𝕜$ of type BaseRingType.
Morphisms of schemes shall be derived from the abstract type
SchemeMor — TypeSchemeMor{DomainType, CodomainType, MorphismType, BaseMorType}A morphism of schemes $f : X → Y$ of type MorphismType with $X$ of type DomainType and $Y$ of type CodomainType.
When $X$ and $Y$ are defined over schemes $BX$ and $BY$ other than $Spec(𝕜)$, BaseMorType is the type of the underlying morphism $BX → BY$; otherwise, it can be set to Nothing.