PRIVATE>
-MACRO:: vconvert ( from-type to-type -- )
+MACRO:: vconvert ( from-type to-type -- quot )
from-type new [ simd-element-type ] [ byte-length ] bi :> ( from-element from-length )
to-type new [ simd-element-type ] [ byte-length ] bi :> ( to-element to-length )
from-element heap-size :> from-size