BoundaryML/baml · error

unexpected type for clear result: %T

Error message

unexpected type for clear result: %T

What it means

Go type-assertion failure in the collector's Clear method: the bridge returned the clear result, but it is not an int64 (the %T names the actual type). The runtime and Go bindings disagree on the return shape of 'clear' — typically a version mismatch between the baml runtime and the generated Go library.

Solutions

1. Rebuild against the matching BAML runtime so the return type is int64.
2. Convert defensively in the client if a custom runtime returns another numeric type.
3. Report upstream with the %T value if versions match.

Example fix

// before
count, ok := result.(int64)
// after
count, ok := result.(int64)
if !ok {
	if f, isF := result.(float64); isF { count = int64(f) }
}

if collector == nil { return errors.New("collector not initialized") }

func toInt64(v any) (int64, bool) {
	switch n := v.(type) {
	case int64: return n, true
	case int: return int64(n), true
	case float64: return int64(n), true
	}
	return 0, false
}

count, err := collector.Clear()
if err != nil {
	if strings.Contains(err.Error(), "unexpected type") { /* numeric type skew between runtimes */ }
	return err
}

When it happens

Trigger: collector.Clear() where CallMethod returns a non-int64 (e.g. int, uint64 from a differently-built runtime, or nil).

Common situations: Mixed Go/native versions where the runtime returns a different numeric width/type; runtime returning nil on clear.

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

• unexpected type for last log: %T
• unexpected type for log by id: %T
• unexpected type for logs: %T
• unexpected type in logs: %T
• failed to clear

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/75c67fdb852f2ebd. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_client_go/pkg/rawobjects_collector.go:120

	}

	log, ok := result.(FunctionLog)
	if !ok {
		return nil, fmt.Errorf("unexpected type for log by id: %T", result)
	}

	return log, nil
}

func (c *collector) Clear() (int64, error) {
	result, err := raw_objects.CallMethod(c, "clear", nil)
	if err != nil {
		return 0, fmt.Errorf("failed to clear: %w", err)
	}

	count, ok := result.(int64)
	if !ok {
		return 0, fmt.Errorf("unexpected type for clear result: %T", result)
	}

	return count, nil
}

View on GitHub (pinned to bd85ce9dee)