What kind of diagram are you wanting to make?

Idea or feature request
Adding support for arrows.rl as found on https://typst.app/docs/reference/symbols/sym/

Alternatives you've considered
using the shift parameter

edge((i, 2), (i + 1, 2), "<-", $∂'_(i-1)$, shift: 3pt),
edge( (i, 2), (i + 1, 2), "->", $δ_(i)$, shift: -3pt, label-side: right,)

resulting in this

Additional context