lines/unlines and "inverse"

[Wolfgang Jeltsch]

On Monday, 2002-07-22, 11:25, CEST, Koen Claessen wrote:
> Lars Henrik Mathiesen wrote:
> 
>  | lines . unlines = id
>  | unlines . lines . unlines == unlines
>  | words . unwords . words = words
> 
> Don't be fooled by the information content of the second
> equation -- the first equation directly implies it:
> 
>   unlines . lines . unlines    == {assoc (.)}
>   unlines . (lines . unlines)  == {equation 1}
>   unlines . id                 == {id is unit of (.)}
>   unlines

Yes, but the first equation is not true because, e.g.,
    lines (unlines ["\n"]) = ["",""].

> [...]

Wolfgang