Vector and hash table modifiers that return vectors and hash tables?

[ornamentist]

The Coalton standard library provides vector and hash table data structures. These data structures are equipped with constructor functions (e.g. with-capacity), query function (e.g. head) and modifiers (e.g. push!).

I think the modifier functions would be more ergonomic in a FP environment if they returned a new vector or hashtable rather than modifying the argument in place? I can see this could lead to:

• The rabbit-hole of immutable data structures
• Performance (copying) issues

How are other Coalton developers approaching this issue?