I want to learn some math with haskell, so currently I want to get the math limit of a function
in rust I did 
```rust
fn limit(f: impl Fn(f32) -> f32, l: f32, dir: Dir) -> f32 {
   	let mut cursor = if matches!(Dir::R, dir) {l + 1.} else { l - 1.};
   	let mut f_val = None;
   	loop {
   	   	let new_f_val = f(cursor);
   	   	if Some(new_f_val) == f_val {
   	   	   	break new_f_val
   	   	}
   	   	cursor /= 10.;
   	   	f_val = Some(new_f_val);
   	}
}

```
I'm not sure how to translate it to haskell, or if there is a builtin way to do it