&gt; I just said that classifying non-linear transfer of control (whether exceptions or proper continuation) as an effect at all is quite arbitrary, and is just a common usage in the PFP world.<p>What exactly makes it arbitrary? It&#x27;s pretty sensible, even if you don&#x27;t have substructural types.<p>&gt; Of course, substructural types are also a language concept (that does indeed interact badly with non-local jumps)<p>Control effects and substructural types don&#x27;t interact “badly”. They just require care if you want them together. If you desugar control effects into delimited continuations (that is, normal higher-order functions), it becomes clear as daylight how to correctly handle their interaction with substructural types.