splitp_blocks :: (Block m l -> Bool) -> BlockEnv (Block m l) ->
Maybe (Block m l, BlockEnv (Block m l))
-splitp_blocks = undefined -- implemented in ZipCfg but not exported
+splitp_blocks = panic "splitp_blocks" -- implemented in ZipCfg but not exported
is_exit :: Block m l -> Bool
-is_exit = undefined -- implemented in ZipCfg but not exported
+is_exit = panic "is_exit" -- implemented in ZipCfg but not exported