User-defined data types Mapping

The constructors of Sum/Product algebraic data types are mapping to tuples in Erlang at compile-time.

Hamler:

  1. -- Sum datatype
  2. data Color = Red | Green | Blue
  3. Red   -- {'Red'}
  4. Green -- {'Green'}
  5. Blue  -- {'Blue'}
  7. -- Product datatype
  8. data Pair = Pair Integer Integer
  9. Pair 3 4 -- {'Pair',3,4}
  11. -- Maybe
  12. data Maybe a = Just a | Nothing
  13. Nothing -- {'Nothing'}
  14. Just 5  -- {'Just',5}

Erlang:

  1. {'Red'}   %% Red
  2. {'Green'} %% Green
  3. {'Blue'}  %% Blue
  5. {'Pair',3,4} %% Pair 3 4
  7. {'Nothing'} %% Nothing
  8. {'Just',5}  %% Just 5