Stackoverflow https://stackoverflow.com/questions/69418700/why-doesnt-this-fixed-point-computation-stop

ghci.hs

λ> :{
 > second (x:y:xs) = y : second xs  -- returns every second element of a list
 > second _ = []
 > 
 > xs = [1,2,3,4] ++ second xs
 > :}
λ> second [1,2,3,4]
[2,4]
λ> second $ second [1,2,3,4]
[4]
λ> second $ second $ second [1,2,3,4]
[]
λ> second $ second $ second $ second [1,2,3,4]
[]
-- we can repeat this ad nauseam 

xs = [1,2,3,4] ++ second xs
xs = [1,2,3,4] ++ second ([1,2,3,4] ++ second xs)
xs = [1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second xs)))
xs = [1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second ([1,2,3,4] ++ second xs)))))))

It just occurred to me. The ideal example is xs = [] ++ second xs.