showPs env ((n, _, Let _ t v) : bs) =
    "  " ++ show n ++ " : "
        ++ showEnv env ({- normalise ctxt env -} t)
        ++ "   =   "
        ++ showEnv env ({- normalise ctxt env -} v)
        ++ "\n"
        ++ showPs env bs
showPs env ((n, _, b) : bs) =
    "  " ++ show n ++ " : "
        ++ showEnv env ({- normalise ctxt env -} (binderTy b))
        ++ "\n"
        ++ showPs env bs
