prestodb/presto · error · SemanticException

STANDALONE_LAMBDA

STANDALONE_LAMBDA

Error message

Lambda expression should always be used inside a function

What it means

Analysis error: a lambda expression appeared outside of a function call context. Lambdas in Presto only have meaning as arguments to higher-order functions (map/filter/transform etc.); a bare lambda in an expression list or standalone position is rejected by this guard in the analyzer.

Source

Thrown at presto-main-base/src/main/java/com/facebook/presto/sql/analyzer/ExpressionAnalyzer.java:1616

                default:
                    throw new IllegalStateException(format("Unexpected comparison type: %s", node.getOperator()));
            }

            return setExpressionType(node, BOOLEAN);
        }

        @Override
        public Type visitFieldReference(FieldReference node, StackableAstVisitorContext<Context> context)
        {
            Field field = baseScope.getRelationType().getFieldByIndex(node.getFieldIndex());
            return handleResolvedField(node, new FieldId(baseScope.getRelationId(), node.getFieldIndex()), field, context);
        }

        @Override
        protected Type visitLambdaExpression(LambdaExpression node, StackableAstVisitorContext<Context> context)
        {
            if (!context.getContext().isExpectingLambda()) {
                throw new SemanticException(STANDALONE_LAMBDA, node, "Lambda expression should always be used inside a function");
            }

            List<Type> types = context.getContext().getFunctionInputTypes();
            List<LambdaArgumentDeclaration> lambdaArguments = node.getArguments();

            if (types.size() != lambdaArguments.size()) {
                throw new SemanticException(INVALID_PARAMETER_USAGE, node,
                        format("Expected a lambda that takes %s argument(s) but got %s", types.size(), lambdaArguments.size()));
            }

            ImmutableList.Builder<Field> fields = ImmutableList.builder();
            for (int i = 0; i < lambdaArguments.size(); i++) {
                LambdaArgumentDeclaration lambdaArgument = lambdaArguments.get(i);
                Type type = types.get(i);
                fields.add(com.facebook.presto.sql.analyzer.Field.newUnqualified(lambdaArgument.getLocation(), lambdaArgument.getName().getValue(), type));
                setExpressionType(lambdaArgument, type);
            }

View on GitHub (pinned to 55bb57d202)

Solutions

1. Place the lambda inside a higher-order function, e.g. filter(a, x -> x > 0)
2. Replace the bare lambda with a regular expression
3. Check for a missing function name or misplaced parenthesis

When it happens

Trigger: Thrown at presto-main-base/src/main/java/com/facebook/presto/sql/analyzer/ExpressionAnalyzer.java:1616 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/ff3314b7a8f73cf8. Report an issue: GitHub.