30 lines
488 B
Text
30 lines
488 B
Text
data Maybe (a) where {
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Nothing : Maybe (a)
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Just : a -> Maybe (a)
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};
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fmap : (a -> b) -> Maybe (a) -> Maybe (b) ;
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fmap f ma = case ma of {
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Nothing => Nothing ;
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Just a => Just (f a) ;
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};
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pure : a -> Maybe (a) ;
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pure x = Just x ;
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ap mf ma = case mf of {
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Just f => case ma of {
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Nothing => Nothing;
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Just a => Just (f a);
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};
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Nothing => Nothing;
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};
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return = pure;
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bind ma f = case ma of {
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Nothing => Nothing ;
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Just a => f a ;
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};
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