Compatibility summary
You will need a travel adapter in Haiti; plug types used there differ from Singapore. Voltage differs by more than 20% — a voltage converter may be needed for some appliances.
Plug comparison
Singapore plug types: G
Haiti plug types: A B
There is no common plug type between Singapore (G) and Haiti (A B). You need a travel adapter.
Voltage comparison
Singapore: 230V, 50Hz
Haiti: 110V, 60Hz
Voltage converter recommended (Singapore 230V vs Haiti 110V).