Comma quibbling is a task originally set by Eric Lippert in his blog.



Task

Write a function to generate a string output which is the concatenation of input words from a list/sequence where:

 An input of no words produces the output string of just the two brace characters "{}".
 An input of just one word, e.g. ["ABC"], produces the output string of the word inside the two braces, e.g. "{ABC}".
 An input of two words, e.g. ["ABC", "DEF"], produces the output string of the two words inside the two braces with the words separated by the string " and ", e.g. "{ABC and DEF}".
 An input of three or more words, e.g. ["ABC", "DEF", "G", "H"], produces the output string of all but the last word separated by ", " with the last word separated by " and " and all within braces; e.g. "{ABC, DEF, G and H}".


Test your function with the following series of inputs showing your output here on this page:

 [] # (No input words).
 ["ABC"]
 ["ABC", "DEF"]
 ["ABC", "DEF", "G", "H"]


Note: Assume words are non-empty strings of uppercase characters for this task.




fn q(s []string) string {
    match s.len {
        0 {
            return '{}'
        }
        1 {
            return '{${s[0]}}'
        }
        2 {
            return '{${s[0]} and ${s[1]}}'
        }
        else{
            return '{${s[0..s.len-1].join(', ')} and ${s[s.len-1]}}'
        }
    }
}
 
fn main(){
    println(q([]))
    println(q(['ABC']))
    println(q(['ABC','DEF']))
    println(q(['ABC','DEF','G','H']))
}