User-defined Types

Hamler supports algebraic data types (ADTs):

  1. -- type synonym
  2. type Name = String
  3. "Miles" :: Name
  4. "Miles" :: String
  6. newtype UInt8 = UInt8 Integer
  7. 1 :: Integer
  8. UInt8 1 :: UInt8
  10. -- sum datatype
  11. data Color = Red | Green | Blue
  12. Blue :: Color
  14. -- product datatype
  15. data Pair = Pair Integer Integer
  16. Pair 3 4 :: Pair
  18. -- record product datatype
  19. data Person = Person {
  20.   name :: String
  21.   age :: Integer
  22.   address :: String
  23. }
  24. Person {name = "Miles", age = 50, address = "NY"} :: Person
  26. -- generic datatype (maybe for example)
  27. data Maybe a = Just a | None
  28. data Result val err = Ok val | Error err
  30. -- recursive datatype
  31. data Tree = Leaf Integer | Node Tree Tree