loom

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import "Exception" type Exception
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// Module interface declaration
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interface Factorial : immutable, throw (Exception) {
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    pure factorial(int n) -> int
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}
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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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    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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