[vector] Vector.cast

[Paul Sandoz]

Hi,

Would it make sense to simplify Vector.cast to species of the same length? if length differs an exception is thrown.

That’s one less thing to think about and same concept can then be applied to Shuffle and Mask, which is effectively a nop if no boxing occurs because the underlying lane elements don't change.

We can lean on the reshape/rebracket/resize for other length transforming operations, in addition to mask/shuffle conversion to/from vector.

Paul.