How to pass by reference in XCAS ?

[Albert Chan]

You can emulate pass by reference by putting data inside a list

XCas> add1(lst) := {local I; for I from 1 to len(lst) do lst(I) += 1 end}
XCas> a := [1,2,3]
XCas> add1(a)       → [2, 3, 4]
XCas> add1(a)       → [3, 4, 5]