operatorNotDefined2

operatorNotDefined2

Error message

operatorNotDefined ${leftClass} (via operatorNotDefined helper)

What it means

`||` short-circuit specialization requires the right operand to be Boolean; a non-Boolean result triggers operatorNotDefined, reported as operatorNotDefined2 for `||`. Same family as the LogicalAndNode failure, only for logical-or.

Source

Thrown at pkl-core/src/main/java/org/pkl/core/ast/expression/binary/LogicalOrNode.java:36

import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.NodeInfo;
import com.oracle.truffle.api.nodes.UnexpectedResultException;
import com.oracle.truffle.api.source.SourceSection;
import org.pkl.core.ast.ExpressionNode;

@NodeInfo(shortName = "||")
public abstract class LogicalOrNode extends ShortCircuitingExpressionNode {
  protected LogicalOrNode(SourceSection sourceSection, ExpressionNode rightNode) {
    super(sourceSection, rightNode);
  }

  @Specialization
  protected boolean eval(VirtualFrame frame, boolean left) {
    try {
      return left || rightNode.executeBoolean(frame);
    } catch (UnexpectedResultException e) {
      throw operatorNotDefined(false, e.getResult());
    }
  }
}

View on GitHub (pinned to f3efcbfc9b)

Solutions

Convert the right side into a Boolean-valued expression
Fix the type of the property used on the right
Annotate the property as Boolean to catch it earlier

Example fix

// before (Pkl)
val useTls = false || "auto"
// after
val useTls = false || (mode == "tls")

Defensive patterns

Strategy: type-guard

Validate before calling

function isValidOrOperand(right) { return typeof right === 'boolean'; }

Type guard

const isBool = (v) => typeof v === 'boolean';

Prevention

Replace `x || default` with explicit comparisons or `??` for nullable defaults
Annotate referenced properties as Boolean
Validate lazy/defaulted properties actually produce Booleans

When it happens

Trigger: `false || <nonBoolean>` e.g. `false || "yes"` or `flag || value` where `value` is an Int/String.

Common situations: Truthy-value assumptions ported from dynamic languages, or a fallback default that is a non-Boolean (e.g. `enabled || "auto"`).

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/6c43cfe94c9b24c4. Report an issue: GitHub.