cycle
有限リストを引数に取り、それを無限に繰り返す
cycle :: HasCallStack => [a] -> [a]
https://hackage.haskell.org/package/base-4.19.0.0/docs/Prelude.html#v:cycle
code:hs
>> cycle []
*** Exception: Prelude.cycle: empty list
>> cycle
2, 5, 7
2,5,7,2,5,7,2,5,7,2,...