Palindromic Expression for Phi

Some find that APL expressions can have a poetic beauty. Phil Last submitted the following variable-free recursive dfn to compute the limit of a converging function, equivalent to the derived monadic operator <source lang=apl inline>⍣≡</syntaxhighlight>: <source lang=apl> limit←{ ⍝ Function power limit (fixpoint).

   ⍵ ⍺⍺{           ⍝ 'old' value:
       ⍺≡⍵:⍵       ⍝       old matches new: finished.
       ⍵ ∇ ⍺⍺ ⍵    ⍝       otherwise: try new value.
   }⍺⍺ ⍵           ⍝ 'new' value.

} </syntaxhighlight> John Scholes noted that it was close to being a palindrome, so he inlined it and he amended it with dummy code to make its invocation for finding the golden ratio even closer to palindromic: <source lang=apl>

     1{1+÷⍵}{⍵ ⍺⍺{⍺≡⍵:⍵ ⋄ ⍵ ⍺⍺ ∇∇ ⍺⍺ ⍵ ⋄ ⍵:⍵≡⍺}⍺⍺ ⍵}{⍵÷+1}1

1.618033989 </syntaxhighlight> Scholes then published a minute-long video with musical accompaniment where he types the expression in a symmetric fashion, culminating with the execution.