It’s not exactly a language but the Emacs calculator (aka GNU Calc) can do a lot of the things J does for the author. Product of factorials would be: v M ! v

It’s not exactly a language but the Emacs calculator (aka GNU Calc) can do a lot of the things J does for the author. Product of factorials would be: v M ! v R * Where the v may be capitalised if you like and the spaces are the way the commands are written but aren’t typed. That decomposes into some easy mnemonics: Vector Map factorial, Vector Reduce multiplication. It has a bunch of mathematical features, a quick interface for plotting simple graphs (with gnuplot), some symbolic algebra, and it sort-of has the reactive feature too. (I think there’s also a mode for using it in files). Date handling is ok but simple (a date/time is internally represented as a Julian day so if you add 1 to a date/time you get the next day; times go into the fractional part. Leap seconds / time zones aren’t handled. There is an option to configure when your calendar switched from Julian to Gregorian. It’s usually fast enough for what I use it for but it can be limited by performance.