Question: I need to convert string to letter case (proper case or title case), is there any default function on Groovy support for this or I need to manual sub string convert first character?

Answer: 
yes, you can use the method capitalize() 

<http://groovy.codehaus.org/groovy-jdk/java/lang/String.html#capitalize%28%29>
I got it, here is solution for those who needed

```
def capitalize(s) { s[0].toUpperCase() + s[1..-1].toLowerCase() }
caps = "man OF stEEL".replaceAll(/\w+/) { w -> capitalize(w) }

```