Using closures when a function pointer can be used instead can negatively impact readability and maintainability of the code. Closures can obscure the intent of the code, making it harder for other developers to understand what the code is doing at a glance. Function pointers, on the other hand, are more explicit and can make the code more concise and easier to read.
Replace closures with function pointers when the closure simply calls a function. This makes the code more readable and easier to understand.
let result = Some('a').map(|s| s.to_uppercase());
let result = Some('a').map(char::to_uppercase);