List sum shouldn't take quadratic time

[Negabinary]

let list_of_ones : Int -> [Int] = fun n ->
  if n == 0 then [] else 1 :: list_of_ones(n-1)   
in

let sum : [Int] -> Int = fun l ->
  case l
    | [] => 0
    | x::xs => x + sum(xs)  
  end   
in

let n = 2000 in

sum(list_of_ones(n))

[Negabinary]

I checked and list_of_ones is linear, but sum is quadratic.

I suspect it's because of this transition rule (possibly my fault). Specifically is_value:false makes variable lookup take O(n) time.

In order to switch to is_value:true, we are going to have to comb through evaluation rules and convince ourselves that everything that goes into a closure (function arguments, fixpoints, builtins, etc.) is always final; which I suspect isn't true now.

[cyrus-]

Only thing that may not be final is a fixpoint...

[Negabinary]

builtin functions are also not currently final, because they have always been stored in the initial environment without a closure (though that should be an easy fix)