A complete list of issues of the hp journal is available at:
It is a gold mine of systems programming languages articles, in a world where C wasn't yet something that actually mattered.
I have J on my phone, and it works well as an advanced programmable calculator.
APL is one of the most unapproachable languages I every learned.
and fig 2 / page 5 is epic
I've played with J, but APL, with the symbols, feels nicer.
Even though it's almost impossible to dictate code to someone when pair programming.