fix: address comments

proto/substrait/algebra.proto

@@ -482,12 +482,12 @@ message Expression {
   message Cast {
     Type type = 1;
     Expression input = 2;
-    ConditionFlag condition_flag = 3;
+    FailureBehavior failure_behavior = 3;
 
-    enum ConditionFlag {
-      CONDITION_FLAG_UNSPECIFIED = 0;
-      CONDITION_FLAG_NULL_ON_FAILURE = 1;
-      CONDITION_FLAG_THROW_ON_FAILURE = 2;
+    enum FailureBehavior {
+      // throw an exception as default failure behavior
+      FAILURE_BEHAVIOR_UNSPECIFIED = 0;
+      FAILURE_BEHAVIOR_RETURN_NULL = 1;
     }
   }
 

site/docs/expressions/specialized_record_expressions.md

@@ -11,9 +11,7 @@ For each data type, it is possible to create a literal value for that data type.
 
 
 ## Cast Expression
-To convert a value from one type to another, Substrait defines a cast expression. Cast expression declares an expected type, an input argument and an enumeration flag that contains enhancement conditions, such as `CONDITION_FLAG_NULL_ON_FAILURE` which  prevents throws and instead returns null on cast failure.
-
-
+To convert a value from one type to another, Substrait defines a cast expression. Cast expressions declare an expected type, an input argument and an enumeration specifying failure behavior, indicating whether cast should return null on failure or throw an exception.
 
 ## If Expression
 An if value expression is an expression composed of one if clause, zero or more else if clauses and an else clause. In pseudocode, they are envisioned as: