loom

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// Module interface declaration
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interface Factorial : immutable {
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    pure factorial(int n) -> int
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}
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import "Exception" Exception
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// Defining module functions
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pure factorial(int n)
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->   int
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{
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    try {
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        if (n <= 0)
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            throw Exception("factorial", "Invalid argument value")
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        return (n == 1) ? 1 : n*factorial(n-1)
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    }
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    catch (Exception e) {
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        return 1
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    }
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}
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