2015-04-20 18:12:09 +00:00
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And now we can do sanity checks:
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\begin{haskellcode}
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calcSomething :: Int -> MaybeInt
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calcSomething x
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| x < 100 = NoError (x * 5)
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| otherwise = Error "Int out of range!"
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\end{haskellcode}
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\pause
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2015-04-19 22:32:01 +00:00
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And pattern match on it as well:
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\begin{haskellcode}
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addIntToList :: MaybeInt -> [Int]
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addIntToList (NoError x) = [x]
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addIntToList (Error str) = []
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\end{haskellcode}
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So if we got an error, we just return an empty list, otherwise we return a list with the \code{Int} as its only element.
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