29 lines
953 B
Haskell
29 lines
953 B
Haskell
module GOL.Rule where
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-- | The rule of a Conway's Game of Life simulation
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-- describes how a cell changes based on its surrounding
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-- cells. The official GOL uses one standard rule, but
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-- this engine allows for an arbitrary rule to be applied.
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--
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-- A rule consists of two predicates that take a value
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-- in the range [0..8], the count of alive cells neighboring
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-- the current cell, and returns whether that cell will be
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-- alive in the next generation.
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data Rule = Rule
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{ -- | A predicate deciding if an alive cell
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-- will be alive in the next generation.
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survive :: Int -> Bool,
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-- | A predicate deciding if a dead cell
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-- will be alive in the next generation.
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birth :: Int -> Bool
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}
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-- | Construct a rule by giving lists of
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-- values that satisfy each predicate.
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rule :: [Int] -> [Int] -> Rule
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rule s b = Rule (`elem` s) (`elem` b)
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-- | The standard GOL rule (S23/B3).
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standardRule :: Rule
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standardRule = rule [2, 3] [3]
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