April 10, 2026
Flattening lists, inflated drama
War on Raze
Tiny code, big chaos: awe, confusion, and TempleOS jokes
TLDR: A K programmer tried to ditch a flattening trick (“raze”) using an APL-style move and hit a type error, reigniting K vs. APL debates. Commenters split between mind-blown wonder and “this is just weird,” with jokes about a sequel—proof that tiny code can spark big feelings.
A lone hacker launched a cheeky “War on Raze” — trying to avoid a list‑flattening trick in the ultra-terse K language — and promptly dove into an APL-inspired rabbit hole. The plan: swap out flattening for a “deep where” move borrowed from APL’s ⍸, aiming to keep data tidy while generating prime-number magic. Result? A dramatic type error cliffhanger and a fresh spark in the old K vs. APL rivalry, with links flying to the K wiki and APL lore.
The comments are the real show. One reader confessed to feeling like there’s “a universe hiding in plain sight under the universe you’ve always known,” dazzled and disoriented by symbol soup. Another fired a spicy shot, likening K to something “halfway between TempleOS and MUMPS,” arguing this isn’t deep philosophy — it’s just written in a delightfully bizarre dialect. And then came the sequel bait: “Next up – the War on Lambdas,” because nothing says Friday night like fighting anonymous functions.
Between the awe-struck and the eye-rollers, the thread turned into a cult-classic debate on esoteric languages: high art or high nonsense? Either way, everyone’s tuning in for the fix, the sequel, and more one-liner wizardry that makes your brain melt — in a good way.
Key Points
- •A concise k7 prime filter uses rank-sensitive ‘except’ (^) to remove composite products from a list of 2..99.
- •Before May 2019, the solution required raze (,/), and the rank-sensitive ‘except’ update enabled a shorter, flatter approach.
- •An alternative raze-free method generates index pairs via odometer (!) and indexing (@), achieving similar speed but with more complexity.
- •The article distinguishes shallow versus deep verbs and proposes using a deep where to produce flat pairs from a keyed matrix.
- •Deep where is not available in k7; Dyalog APL provides ⍸, and ngn/k offers an experimental version, but applying it to a keyed table led to a type error.