If the value of a variable is a list with even length, then it is an array and a dict at the same time.
You can lappend to any variable.
set Var(1) a → {1 a}
dict get $Var 1 → a
lappend Var 2 → {1 a 2}
array get Var → missing value to go with key
dict get $Var 1→ missing value to go with key
array set Var {3 c} → missing value to go with key
array exists Var → 0
lappend Var b → {1 a 2 b}
array exists Var → 1
Moral: You can kill your arrays with list operations.