I had a blast learning to write and read APL for a course at my university where we chose and presented the papers from HOPL IV. If you want a fairly quick and

I had a blast learning to write and read APL for a course at my university where we chose and presented the papers from HOPL IV. If you want a fairly quick and easy read about the history of APL I can heartily recommend the paper "APL Since 1978". A small taste: `twoSum ← {1↑⍸⍺=(⍵∘.+⍵)}`, a dyadic function to find the indicies of (the) two elements in an array that sum to ⍺, for example: `9 twoSum 2 7 11 15` will return `0 1`. Though I doubt I'll ever write any larger programs with it, I've had a lot of fun with it.