Letter Casing in Go

Letter casing functions are available in the core strings package and always have Unicode semantics.

lowercase = strings.ToLower(str)
uppercase = strings.ToUpper(str)
titlecase = strings.ToTitle(str)  // every character
titlecase = strings.Title(str)    // first character of each word

Although there is no case folding function for strings, there is a caseless equality function that uses case folding,

strings.EqualFold(str1, str2)