Long-time programmer/newbie with Haskell...
Thought I'd check out a program I saw at
https://programmingpraxis.com/2019/12/13/pentabonacci-numbers/#comments:
pdiv (a:s) t = a : pdiv (zipWith (-) (s ++ repeat 0) (map (*a) t)) t
take 20 (pdiv [1] [-1,-1])
take 20 (pdiv [0,1] [-1,-1,-1,-1,-1])
I entered at the Haskell Online Compiler (
https://paiza.io/projects/HEXouZ1jmJjemSO1cULHoA?language=haskell) and on my iOS Haskell app and got the same error:
[1 of 1] Compiling Main ( Main.hs, Main.o )
Main.hs:3:1: error:
Parse error: naked expression at top level
Perhaps you intended to use TemplateHaskell
Interestingly on my Windows 10 GHCi app, it worked fine:
GHCi, version 8.4.3:
http://www.haskell.org/ghc/ :? for help
Prelude> pdiv (a:s) t = a : pdiv (zipWith (-) (s ++ repeat 0) (map (*a) t)) t
Prelude> take 20 (pdiv [1] [-1,-1])
[1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765]
Prelude> take 20 (pdiv [0,1] [-1,-1,-1,-1,-1])
[0,1,1,2,4,8,16,31,61,120,236,464,912,1793,3525,6930,13624,26784,52656,103519]
Prelude>
I'm sure it's some formatting issue. I would appreciate any assistance you folks could offer.
Thanks, Steve