- [½] existential types
- Return tuples
- accept path to BLAS as argument
- SIMD in IR rather than too functional
- start with 128-bit pairs for copy?
- "return tuple as two registers"
- return array as stack-allocated
- "return data view" when some necessary parameters (e.g. dimension, rank) are known—e.g. for sliding window, don't need to copy an intermediate