module V = Value
module T = Term

let rec index : V.env -> int -> V.value
  = fun env i ->
    match env with
    | []      -> failwith "Can't happen"
    | x :: xs -> if i < 1 then x else index xs (i-1)

let rec eval : V.env -> t.term -> V.value
  = fun env tr ->
    match tr with
    | Var  i                    -> index env i
    | Type                      -> V.Type
    | T0                        -> V.T0
    | Ind0 (B b, t)             -> failwith "todo"
    | T1                        -> V.T1
    | T1tr                      -> V.T1tr
    | Ind1 (B b, t1 tr)         -> failwith "todo"
    | TNat                      -> V.TNat
    | Zero                      -> V.Zero
    | Suc  n                    -> failwith "todo"
    | IndN (B b, tz, B B ts, n) -> failwith "todo"
    | TBool                     -> failwith "todo"
    | True                      -> failwith "todo"
    | False                     -> failwith "todo"
    | IndB (B b, tt, tf, b)     -> failwith "todo"
    | Pi   (dom, B cod)         -> failwith "todo"
    | Lam  (B body)             -> failwith "todo"
    | App  (f, x)               -> failwith "todo"
    | Sg   (ty, tr)             -> failwith "todo"
    | Pair (x, y)               -> failwith "todo"
    | Fst  tr                   -> failwith "todo"
    | Snd  tr                   -> failwith "todo"