[Haskell-beginners] share a record type

[David Place]

On Jun 17, 2011, at 7:00 AM, Kees Bleijenberg wrote:

> How can I express the fact that all sudoku solvers use the same recordtype? Can I make a type of the record structure {board:: Board.... } and use it in the constructor function or can I incorperate the recordtype in the class or ......?


This is a good use for the "newtype" declaration.  Define your SudokuRecord and then specialize it using newtype.

data SudokoRecord ...

newtype SudokuTwins = SudokuTwins SudokuRecord
newtype Sudoku9x9 = Sudoku9x9 SudokuRecord

instance SudokuClass SudokuTwins where
...


instance SudokuClass Sudoku9x9 where
...

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