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2025-11-04

Last modified: 2025-11-04 16:12:25

< 2025-11-01

Array programming

APL, K, and J are "array programming" languages. I recently read this great blog post https://needleful.net/blog/2024/01/arthur_whitney.html "Learning to read Arthur Whitney's C to become Smart" and was quite fascinated by his strange style of programming.

Is there an actual open source language like this that I could play with?

ChatGPT suggests J. https://jprogramming.com/

Lol, you have to install it from source?

OK, there is https://jsoftware.github.io/j-playground/bin/html2/ which you can get started in.

Precedence is always that right-hand arguments are evaluated first. So 3*2+4*5 is 3*(2+(4*5)).

The more general rule is that for monadic functions the argument comes to the right.

So you can define a monadic function just by assigning something that is missing its argument:

sum =: + /

Because "+ / some_list_object" will "add" (+), "together" (/) the elements of the list. So now our "sum" function will do the same.

Meh, I am too tired to deal with this. It is interesting but I don't think anything has really clicked. I probably want to try to go through some easy Advent of Code problems to see how you use it.

< 2025-11-01