Conversely, after many years of dabbling I still consider myself a complete novice at APL and array programming. However, my studying of array langs made learning LLMs fairly trivial. In particular, studying APL's inner product from the Mastering Dyalog book was the key to understanding the self-attention mechanism from Attention is All You Need and how it communicates semantic information across the positionally encoded tokens.

I'd still probably struggle to do anything mildly complex in APL, though, sadly. It hasn't fully clicked yet, but maybe one day!