Try and eat them between these months as they are at their best then. Longan is a bit slimy looking to me and a taste I did not quite develop a taste for it. It is served cold on many dessert buffet tables at restaurants, especially Thai. A small, round, brown fruit that is in season from June until August and brought to work in bags for sharing. Lychee is a fruit that is good canned or fresh.
Lychees are a small fruit with a brittle skin that peels without any problems.
The pulp is fairly clear with one shiny seed inside. You will frequently see them peeled and in large bowls on dessert buffet tables. Though mango is not native to Singapore, when you see it snap it up. They will be expensive in the Singaporean grocery stores so try and find them at some of the wet markets. These are the outdoor fruit stalls.