Productions
Overwrite action
Canonical ACT-R supports an overwrite buffer operation that performs an end-run around the managing module and also prevents the encoding of previous contents. =goal> =chunk will replace the contents of the goal buffer with =chunk without encoding the current contents.
jACT-R does not support this operation. You can add, remove, modify or request, and that's it. The Lisp parser will tranform overwrites into adds automatically and notify you that this has been done.
Explicit state reset
If a retrieval fails, the only way to reset the state is to complete a successful retrieval. There is no mechanism to explicitly reset the state. While some modules do have this (+visual> isa clear), it is not standard. jACT-R solves this by using an explicit remove operation (-retrieval>). If there is nothing in the buffer, it will have its states reset.