feat: access computed values of relations

1 files changed, 7 insertions, 2 deletions

diff --git a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
index 10e994a0..df33cfa6 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -92,7 +92,7 @@ enum ParameterBinding:
 
 Parameter:
         (
-                (concreteness=Concreteness? modality=Modality)?
+                (derivation=Derivation? concreteness=Concreteness? modality=Modality)?
                 parameterType=[Relation|QualifiedName]
         )? binding=ParameterBinding? name=Identifier;
 
@@ -182,6 +182,9 @@ AggregationExpr:
         aggregator=[AggregatorDeclaration|QualifiedName]
         "{" value=Expr "|" condition=ComparisonExpr "}";
 
+enum Derivation:
+        COMPUTED="computed";
+
 enum Concreteness:
         CANDIDATE="candidate";
 
@@ -189,7 +192,9 @@ enum Modality:
         MUST="must" | MAY="may";
 
 ModalExpr:
-        concreteness=Concreteness? modality=Modality body=UnaryExpr;
+        derivation=Derivation?
+        concreteness=Concreteness?
+        modality=Modality body=UnaryExpr;
 
 CastExpr returns Expr:
         CastExprBody ({CastExpr.body=current} "as" targetType=[Relation|QualifiedName])?;