private void assertPurityForInput <Tin, Tout>(Func <Tin, Tout> func, Tin input, bool isPure)
where Tout : IEquatable <Tout>
{
var funcMemoized = CategoryTheoryForProgrammers.Memoize(func);
Assert.True(funcMemoized(input).Equals(func(input)) == isPure);
Assert.True(funcMemoized(input).Equals(func(input)) == isPure);
}
public void MemoizeRandomSeededWorks()
{
Func <int, double> randomSeeded = (int seed) => { var rand = new Random(seed); return(rand.NextDouble()); };
var randomSeededMemoized = CategoryTheoryForProgrammers.Memoize(randomSeeded);
Assert.True(randomSeededMemoized(42) == randomSeeded(42));
Assert.True(randomSeededMemoized(42) == randomSeeded(42));
}
public void MemoizeRandomDoesNotWork()
{
Func <int, double> random = (int _) => { var rand = new Random(); return(rand.NextDouble()); };
var randomMemoized = CategoryTheoryForProgrammers.Memoize(random);
Assert.True(randomMemoized(42) != random(42));
Assert.True(randomMemoized(42) != random(42));
}
public void CompositionPreservesIdentity()
{
var one = CategoryTheoryForProgrammers.Compose <int, int, int>(CategoryTheoryForProgrammers.Identity, (int a) => - a);
var two = CategoryTheoryForProgrammers.Compose <int, int, int>((int a) => - a, CategoryTheoryForProgrammers.Identity);
Assert.True(one(8) == two(8));
Assert.True(one(-8) == two(-8));
}
public void MemoizeWorks()
{
Func <int, int> addOneLongRunning = (int a) => { Thread.Sleep(50); return(a++); };
var addOneLongRunningMemoized = CategoryTheoryForProgrammers.Memoize(addOneLongRunning);
var time = DateTime.Now;
Console.WriteLine(time);
Assert.True(addOneLongRunning(42) == addOneLongRunning(42));
var runtimeOne = (DateTime.Now - time);
time = DateTime.Now;
Assert.True(addOneLongRunning(42) == addOneLongRunning(42));
var runtimeTwo = (DateTime.Now - time);
Assert.True(runtimeTwo < runtimeOne);
}