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.




import std.stdio, std.string;
 
string quibbler(in string[] seq) pure /*nothrow*/ {
    if (seq.length <= 1)
        return format("{%-(%s, %)}", seq);
    else
        return format("{%-(%s, %) and %s}", seq[0 .. $-1], seq[$-1]);
}
 
void main() {
    //foreach (immutable test; [[],
    foreach (const test; [[],
                          ["ABC"],
                          ["ABC", "DEF"],
                          ["ABC", "DEF", "G", "H"]])
        test.quibbler.writeln;
}