Make eval less aggressive about substitution

src/Lib/Eval.idr

@@ -74,24 +74,8 @@ bind v env = v :: env
 
 -- TODO maybe add glueing
 
--- So this is a tricky bit - I don't want to expand top level functions
--- if I can't get past the case tree.  Kovacs' eval doesn't have the spine
--- when it starts applying. So I'll collect a spine as soon as I see an App
--- Try to apply the Ref, and fall back to vappSpine.
-evalSpine : Env -> Mode -> Tm -> List Val -> M Val
-evalSpine env mode (App _ t u) sp = evalSpine env mode t (!(eval env mode u) :: sp)
-evalSpine env mode (Ref fc nm (Fn tm)) sp = do
-  v <- eval env mode tm
-  let sp' = [<] <>< sp
-  case !(vappSpine v sp') of
-    (VCase x sc xs) => pure $ VRef fc nm (Fn tm) sp'
-    v => pure v
-evalSpine env mode tm sp = vappSpine !(eval env mode tm) ([<] <>< sp)
-
--- This is too aggressive...
--- eval env mode (Ref _ x (Fn tm)) = eval env mode tm
 eval env mode (Ref fc x def) = pure $ VRef fc x def [<]
-eval env mode (App _ t u) = evalSpine env mode t [!(eval env mode u)]
+eval env mode (App _ t u) = vapp !(eval env mode t) !(eval env mode u)
 eval env mode (U fc) = pure (VU fc)
 eval env mode (Meta fc i) =
   case !(lookupMeta i) of