Arrays represented as foreign buffers in the C heap.
Arrays with a representation tag, shape, and element type.
Use one of the type tags like
U and so on for
DIM2 ... for
O(1). Wrap a
ForeignPtr as an array.
Compute an array sequentially and write the elements into a foreign
buffer without intermediate copying. If you want to copy a
pre-existing manifest array to a foreign buffer then
delay it first.