Accessors

Deconstruct values in data model

Example : Attributes

name  : AttrNode -> Ref(QNameValue)
value : AttrNode -> Ref(ValueNode)
type  : AttrNode -> Ref(ElemNode)

<xsd:attribue name="price" type=xsd:decimal/>
<part price=10.50/>

name(A1)  = ref(qnameValue(null, "price"))
value(A1) = ref(decimalValue(10.50, Ref(Def_decimal)))
type(A1)  = <!-- data model representation of simple type decimal -->

Constructors & accessors core operators in XML Query Algebra