Easy as { 1 2 3 }? (when { 1 2 3 } ≠ { 1 2 3 })

[Dave Britten]

Here's a fairly succinct 50g program that uses DOLIST and STREAM to compare elements (and has special cases to handle empty or single-element lists).

Code:


\<<
  DUP2 SIZE SWAP SIZE OVER ==
  \<<
    0. ==
    \<< DROP2 1. \>>
    \<< 2. \<< == \>> DOLIST
      DUP SIZE 1. ==
      \<< LIST\-> DROP \>>
      \<< \<< AND \>> STREAM \>>
      IFTE
    \>>
    IFTE
  \>>
  \<< DROP2 DROP 0. \>>
  IFTE
\>>

You could change the "\<< == \>>" DOLIST argument to do type checking and recursion if you want it to work on nested lists.

Corrections/improvements welcome, as always.