Capitalize first letter of a string

I am quite surprised by the absence of the common function to capitalize the first letter of a string. Yes, we have `toTitle` but its behaviour is different to what we have in other languages. Moreover, docs haven't any hints on that topic. Should a library user implement such method himself? If it is not implemented yet then what problems have this approach?

For example, Scala implements the method as following:

```scala
/** Returns this string with first character converted to upper case.
* If the first character of the string is capitalized, it is returned unchanged.
* This method does not convert characters outside the Basic Multilingual Plane (BMP).
*/
def capitalize: String =
if (s == null || s.length == 0 || !s.charAt(0).isLower) s
else updated(0, s.charAt(0).toUpper)
```

Kotlin developers decided that method has non-reliable behaviour in different circumstances, so they deprecated similar method and instead introduced more flexible alternative `replaceFirstChar` that delegates choosing the type of conversion to user:

```kotlin
public inline fun String.replaceFirstChar(transform: (Char) -> Char): String {
return if (isNotEmpty()) transform(this[0]) + substring(1) else this
}

// Now instead of capitalize() they suggest to use something like:
replaceFirstChar { if (it.isLowerCase()) it.titlecase() else it.toString() }
```

We could have something like that in `text` library. It will help Haskell learners with the knowledge of other languages to adapt to Haskell more quickly.