This seems like a weird complaint - basically everywhere in programming two variables/functions/classes/etc with different names are different things. I'd be much more surprised if appending a ' to a function name did nothing in haskell.
> When you could have just called it foldl and moved the old one to the deprecated module.
1. Most people aren't a fan of randomly changing existing library functions
2. The lazy (non-prime) version of foldl isn't useless! There's even a section at the end of the post explaining how this post _only applies to lists_ and that with other data structures foldl and foldr' are actually useful.
> When you could have just called it foldl and moved the old one to the deprecated module.
1. Most people aren't a fan of randomly changing existing library functions
2. The lazy (non-prime) version of foldl isn't useless! There's even a section at the end of the post explaining how this post _only applies to lists_ and that with other data structures foldl and foldr' are actually useful.