T7230.hs:48:32: error:
    • Could not deduce: (x :<<= x1) ~ 'True
      from the context: Increasing xs ~ 'True
        bound by the type signature for:
                   crash :: (Increasing xs ~ 'True) =>
                            SList xs -> SBool (Increasing xs)
        at T7230.hs:47:1-68
      or from: xs ~ (x : xs1)
        bound by a pattern with constructor:
                   SCons :: forall (k :: BOX) (x :: k) (xs :: [k]).
                            Sing x -> Sing xs -> Sing (x : xs),
                 in an equation for ‘crash’
        at T7230.hs:48:8-27
      or from: xs1 ~ (x1 : xs2)
        bound by a pattern with constructor:
                   SCons :: forall (k :: BOX) (x :: k) (xs :: [k]).
                            Sing x -> Sing xs -> Sing (x : xs),
                 in an equation for ‘crash’
        at T7230.hs:48:17-26
      Expected type: SBool (Increasing xs)
        Actual type: SBool (x :<<= x1)
    • In the expression: x %:<<= y
      In an equation for ‘crash’:
          crash (SCons x (SCons y xs)) = x %:<<= y
    • Relevant bindings include
        y :: Sing x1 (bound at T7230.hs:48:23)
        x :: Sing x (bound at T7230.hs:48:14)