For J, IMO, jsoftware.com has good resources. That includes vocabulary (the way to specify the language), a few textbooks (JforC, J Primer), essays, examples of

For J, IMO, jsoftware.com has good resources. That includes vocabulary (the way to specify the language), a few textbooks (JforC, J Primer), essays, examples of short code... And J forums are pretty helpful. Coming back to the question, for J its vocabulary on jsoftware.com is a good resource.