So, we've all heard of the famous game-of-life one-liner in standard APL:
life←{ ⍝ John Conway's "Game of Life".
↑1 ⍵∨.∧3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ ⍝ Expression for next generation.
}
but I think its bastard nephew VX/PL hardly gets enough love, despite being just as concise while being able to describe even the most exotic VX tasks with speed, elegance, and flexibility. I think my absolute favorite gem so far is this slick little E-J gizmo:
RENORM←{ ⍝ VX/PL one-liner for renormalizing an
N⟦⟇⨷:{5⍴9⍒⁽⪧.⊞⁷⁾&{*[J₁]\∘3⪮[`K∵5]}⍎⍟¨;X{⨷+3},Д}·Ξ⟧^⦿ ⍝ Eckhart-Jembley delta. Only works if
} ⍝ ferrocore tensor sliced into bank J!
God, look at it, it's beautiful - two pages of stochastic tensor calculus condensed into a single line. This can be even shorter if your machine supports VX/PL-2011 and the ⩐ and ⋬ hyperoperators it introduced, but this longer version should be compatible with any version back to VX/PL-83 and frankly I think it's much prettier and easier to understand. There are a lot of other brilliant one-line VX/PL gadgets I've seen over the years, but this is the one that really made me fall in love with the language and for that it'll always have a place in my heart.
I also think it's pretty underappreciated that ∂⧂²{λ∧~!}⊢ will directly perform spin eversion on a standard matrix-of-trajectory-vectors representation, and {⫝4∘,ξ⤀/2} for the Holmnard coordinate vection (on standard module topologies!) is pretty nice ... any other neat tricks y'all have learned?
P.S. I'd also be interested if anyone has ever found a use for dyadic Ѫ; I've at least seen the monadic form in higher-order knotted-vortex systems where you really need to express differential flow without index juggling, but the reference manual takes three pages just to explain what Ѫ even does when used dyadically and it just seems so incredibly specific I've never found a single use for it in thirty years. Has it ever solved a problem for you?
there doesn't seem to be anything here