A few starter generic compute kernels #254

Describe the enhancement requested

I have been hand-writing a pile of generic kernels for numerical arrays and wanted to know what would be required to contribute them upstream.

So far I have implementations for:

• public static Array Filter(Array array, BooleanArray mask)
• public static BooleanArray Equal<T>(PrimitiveArray<T> lhs, T rhs) where T: struct, INumber<T>
• public static BooleanArray Equal<T>(PrimitiveArray<T> lhs, PrimitiveArray<T> rhs) where T: struct, INumber<T>
• public static Array Take(Array array, IList<int> indices)
• public static Int64Array CastInt64<T>(PrimitiveArray<T> array) where T: struct, INumber<T>
• public static Int32Array CastInt32<T>(PrimitiveArray<T> array) where T : struct, INumber<T>
• public static FloatArray CastFloat<T>(PrimitiveArray<T> array) where T : struct, INumber<T>
• public static DoubleArray CastDouble<T>(PrimitiveArray<T> array) where T : struct, INumber<T>

I also have a generic visitor for converting Large* arrays to their regular counterparts so that they may work with the other machinery in the library. I am less confident that is useful to others, or that it is truly correct.

Is there a particular pattern you would want these to follow or is the notion not suitable for the .NET ecosystem? I am less familiar with .NET as an ecosystem.

Thank you.