I’m disappointed by the HN crowd in this thread. Almost nothing brought up as a “similar tool” to Cog actually does what Cog does. Except ‘ot’ who gets it because they actually implemented something similar. I guess this is evidence of Cog’s uniqueness.
Lips seems similar, but for Lisp/Scheme (e.g. https://github.com/zc1036/lips https://github.com/rbryan/guile-lips )