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.




words_series(Words, Bracketed) :-
    words_serialized(Words, Serialized),
    atomics_to_string(["{",Serialized,"}"], Bracketed).
 
words_serialized([], "").
words_serialized([Word], Word) :- !.
words_serialized(Words, Serialized) :-
    append(Rest, [Last], Words),                                  %% Splits the list of *Words* into the *Last* word and the *Rest* 
    atomics_to_string(Rest, ", ", WithCommas),                     
    atomics_to_string([WithCommas, " and ", Last], Serialized).
 
 
 
test :-
    forall( member(Words, [[], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]]),
            ( words_series(Words, Series),
              format('~w ~15|=> ~w~n', [Words, Series]))
          ).