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.




 
# Project : Comma Quibbling
 
text = list(4)
text[1] = "{}"
text[2] = "ABC"
text[3] = "ABC,DEF"
text[4] = "ABC,DEF,G,H"
comma(text)
 
func comma(text)
       listtext = []
       for n = 1 to 4
            listtext = str2list(substr(text[n], ",", nl))
            if n = 2
               see "{" + list2str(listtext) + "}" + nl
               loop
            ok
            if len(listtext) = 1
               see "{}" + nl
               loop
            ok
            str = "{"
            for m = 1 to len(listtext)-1
                if len(listtext) = 2
                   str = str + listtext[m] + " "
                else
                   str = str + listtext[m] + ", "
                ok
            next
            if len(listtext) = 2
               str = left(str, len(str)-1)
            else
               str = left(str, len(str)-2)
            ok
            if len(listtext) = 2
               str = str + " " + listtext[len(listtext)] + "}"
            else
               str = str + " and " + listtext[len(listtext)] + "}"
            ok
            see str + nl
     next
 