expressionDefinition
Defines a named expression. The optional access modifier controls visibility (public is the default). The expression is evaluated lazily when referenced.
Examples
A public expression (default visibility)
define "Adult": AgeInYears() >= 18
A private expression not accessible from other libraries
define private "InInitialPopulation": "Adult" and "HasDiagnosis"
An expression referencing a library-qualified name
define "ActiveConditions": [Condition] C where C.clinicalStatus ~ "Active"
EBNF
expressionDefinition : 'define' accessModifier? identifier ':' expression ;