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.




/* NetRexx */
options replace format comments java crossref symbols nobinary
 
runSample(arg)
return
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method quibble(arg) public static
  parse arg '[' lst ']'
  lst = lst.changestr('"', '').space(1)
  lc = lst.lastpos(',')
  if lc > 0 then
    lst = lst.insert('and', lc).overlay(' ', lc)
  return '{'lst'}'
 
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) private static
  lists = ['[]', -                     -- {}
           '["ABC"]', -                -- {ABC}
           '["ABC", "DEF"]', -         -- {ABC and DEF}
           '["ABC", "DEF", "G", "H"]'] -- {ABC, DEF, G and H}
  loop lst over lists
    say lst.right(30) ':' quibble(lst)
    end lst
  return
 