@EriktheOutgolfer But you never write Stencil program 4 5. Using the operator in APL, you'd write 'program'Stencil 4 5 but I think consensus is to not count spaces (or dashes) for various options and flags in TIO.
@noidd @kaepora We do love a challenge - yes we can do it in 123 characters:
KSA←{S⊣⍵∘{S[⌽p]←S[p←⍵,j←256|j+S[⍵]+⍺[⍵|⍨≢⍺]]}¨S←⍳256⊣j←0}
PRGA←{(S i j)(S[256|+/S[j i]←S[i,j←256|j+S[i←256|i+1⊣S i j←⍵]]])}
Try it online: https://tio.run/#%23SyzI0U2pTMzJT///qG@qp/@jtgkG/72DHYF0dfCjrsWPerc@6phRHRz9qGdvQSxQNDi6AEgChXWygLSRqVlNljZQtndrrPaj3l0gRs2j3hWPOhcBebGxtYdWBIOVbwaqBBoH0mNQyxUQ5A62QSNYIVMhS1MjOBpkkLZ@cHSWQibElkwU8zOh7ExtQ6ApYF0QV8TGxmrW/v9fXFKUmpgLFAI6XQHokVDnYAV1v8SUzFwF7/yk1Mzi4sxHDf3qXBB1XBrFmXnZYKu9gXpArlGAyCgYKBhwAcUVvPGoAYpRVw0A
See more videos from Dyalog '17 at https://dyalog.tv/Dyalog17/?v=xFtK-3CJVgE
This week – U07: Freedom Hunting: Our Search for Independence in UI Design | D09: Cross-Platform User Interfaces using the HTMLRenderer | D11: Literal Notation for Arrays and Namespaces