public void Returns_final_result_after_recursion()
{
RecursionResult <int> Factorial(int k)
{
RecursionResult <int> FactorialAcc(int m, int acc)
{
if (m == 1)
{
return(RecursionResult <int> .Final(acc));
}
return(RecursionResult <int> .Next(() => FactorialAcc(m - 1, m *acc)));
}
return(FactorialAcc(k, 1));
}
Assert.Equal(5 * 4 * 3 * 2 * 1, TailRecursion.Run(() => Factorial(5)));
}
public void Deep_recursion_does_not_blow_the_stack()
{
RecursionResult <BigInteger> Factorial(int k)
{
RecursionResult <BigInteger> FactorialAcc(int m, BigInteger acc)
{
if (m == 1)
{
return(RecursionResult <BigInteger> .Final(acc));
}
return(RecursionResult <BigInteger> .Next(() => FactorialAcc(m - 1, m *acc)));
}
return(FactorialAcc(k, 1));
}
var ex = Record.Exception(() => TailRecursion.Run(() => Factorial(20000)));
Assert.Null(ex);
}
public void Returns_final_result()
{
RecursionResult <int> F() => RecursionResult <int> .Final(1);
Assert.Equal(1, TailRecursion.Run(F));
}
public void Returns_final_result_from_next_iteration()
{
RecursionResult <int> F() => RecursionResult <int> .Next(() => RecursionResult <int> .Final(2));
Assert.Equal(2, TailRecursion.Run(F));
}