Indeed. Many of the high-performance libraries like bytestring, aeson, etc. are written like this.

Haskell's performance is very good for nearly everything I write--and I don't write anything nearly that low level--but I can't deny that this is one of the uglier sides of the language.

On the other hand: In most other languages you'd just be dropping down to the C ABI (that's easy to do in Haskell, too, for that matter.) It is kind of impressive that you can write code that is as fast as C without writing C, even if it is ugly.

The difference is that with Haskell you can wrap a nice, clean, type-safe interface around all that ugly optimization. With C, you're still dealing with casts, null pointer checks, array bounds checks and all sorts of other tedious bug sources that Haskell users don't have to deal with -- unless there's a library bug, of course.

I disagree wholeheartedly on the similar safety guarantees part, Haskell still provides you with a significant amount over C in this case. But it does "look" more like it, if that means anything.