i wrote my own tensor library a while ago and it allows the more convenient matlab/python+numpy like syntax:

a[ _, 9, R(2, $, -3)]

these are allowed:

R() or _: full range for an index

R(a,b): a..b

R(a,b,s): when s>0, iota(a,b,s)

R(a,b,s): when s<0, iota(a,b,-s).reverse

Could we have this in ndslice?