I have been toying with J for the past few years, and I think you only appreciate it when you see it as equivalent to mathematical notation, alien at first, but

I have been toying with J for the past few years, and I think you only appreciate it when you see it as equivalent to mathematical notation, alien at first, but succinct and very useable when you know what the symbols mean. See Iverson's paper on 'Notation as a Tool of Thought' (http://www.jsoftware.com/papers/tot.htm http://www.jsoftware.com/papers/tot.htm). I am self-teaching mathematics, and even when trying Julia as a math tool, I find the basic unit of J, the array, as more amenable to my studies. It's interesting how there is all the talk about 'vectorization' and such in other languages, which J has been doing for decades. J is functional, and can have 'for' loops, but loopless programming is encouraged and easy. When dealing with images or large data sets that are memory mapped, the operations are succinct and powerful and eye-opening. My latest epiphany from moving away from using J as just a sophisticated calculator came after watching the 4 videos by Martin Saurer (https://www.youtube.com/watch?v=VSJpJt3c11c https://www.youtube.com/watch?v=VSJpJt3c11c). Iverson's books on arithmetic and calculus using J are mind-blowing. You are engaged, not distracted by the language. J is fast too. From another talk (https://www.youtube.com/watch?v=IKfJRyoiBlY&feature=youtu.be https://www.youtube.com/watch?v=IKfJRyoiBlY&feature=youtu.be), creating a 1x10^6 element array and summing over columns or rows is fast, and the code is simply: b=: ? 1000 1000 $ 10 +/+/b These two lines create a 1x10^6 element array and then sums the columns, and then sums the single row total. Fast. These guys have really distilled the libraries and made them work well with J (lapacke c interface to lapack). You get c speeds from an interpreter. I guess this is why q with kdb+ is used so much by the finance community despite how expensive it is. Anyway, I am currently staying with J, and I am writing my little tasks in J and julia to see how they fare against each other in speed and development efforts. Now that I have the knowledge to do Qt interfaces for J, I may just stick with J for the sheer joy.