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.




[ swap join join ]                    is glue     ( [ [ [ --> [ )
 
[ [ dup size
    dup 0 = iff
      [ 2drop [] ] done
    dup 1 = iff
      [ drop unpack ] done
    2 = iff
      [ unpack $ ' and ' glue ] done
    behead swap recurse $ ', ' glue ]
  $ '{' swap join $ '}' join ]         is quibble ( [     --> $ )
 
[] quibble echo$ cr
$ 'ABC' nest$ quibble echo$ cr
$ 'ABC DEF' nest$ quibble echo$ cr
$ 'ABC DEF G H' nest$ quibble echo$