Comma quibbling
Comma quibbling is a task originally set by Eric Lippert in his blog.
The task is to 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.
C#
<lang csharp>
public static string Quibble(string[] input) { var len = input.Length; return "{ " + String.Join("", input.Take(len - 2).Select(n => n + ", ") .Concat(input.Skip(len < 2 ? len : len - 2).Take(1).Select(n => n + " and "))) + (input.LastOrDefault() ?? "") + " }"; } static void Main(string[] args) { Console.WriteLine(Quibble(new string[] { })); Console.WriteLine(Quibble(new[] { "A" })); Console.WriteLine(Quibble(new[] { "A", "B" })); Console.WriteLine(Quibble(new[] { "A", "B", "C" })); Console.WriteLine(Quibble(new[] { "A", "B", "C", "D" })); Console.WriteLine(Quibble(new[] { "A", "B", "C", "D", "E" })); }
</lang>
- Output:
{ } { A } { A and B } { A, B and C } { A, B, C and D } { A, B, C, D and E }
D
<lang d>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;
}</lang>
- Output:
{} {ABC} {ABC and DEF} {ABC, DEF, G and H}
F#
<lang fsharp>let quibble list =
let rec inner = function | [] -> "" | [x] -> x | [x;y] -> sprintf "%s and %s" x y | h::t -> sprintf "%s, %s" h (inner t) sprintf "{%s}" (inner list)
// test interactively quibble [] quibble ["ABC"] quibble ["ABC"; "DEF"] quibble ["ABC"; "DEF"; "G"] quibble ["ABC"; "DEF"; "G"; "H"] </lang>
Perl 6
<lang perl6>sub comma-quibbling(@A) {
"\{$_\}" given @A < 3 ?? @A.join(' and ') !! @A[0..*-2].join(',') ~ ' and ' ~ @A[*-1]
}
say comma-quibbling($_) for ((), (<ABC>,), (<ABC DEF>), (<ABC DEF G H>)).tree;</lang>
- Output:
{} {ABC} {ABC and DEF} {ABC,DEF,G and H}
Python
<lang python>>>> def strcat(sequence): # replace(..) can only replace the first X occurrences not the last # Hence the replace is done on the reverse of the intermediate string # then reversed back. return '{%s}' % ', '.join(sequence)[::-1].replace(',', 'dna ', 1)[::-1]
>>> for seq in ([], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]): print('Input: %-24r -> Output: %r' % (seq, strcat(seq)))
Input: [] -> Output: '{}'
Input: ['ABC'] -> Output: '{ABC}'
Input: ['ABC', 'DEF'] -> Output: '{ABC and DEF}'
Input: ['ABC', 'DEF', 'G', 'H'] -> Output: '{ABC, DEF, G and H}'
>>> </lang>
PL/I
<lang pli>*process or(!);
quib: Proc Options(main); /********************************************************************* * 06.10.2013 Walter Pachl *********************************************************************/ put Edit(quibbling())(Skip,a); put Edit(quibbling('ABC'))(Skip,a); put Edit(quibbling('ABC DEF'))(Skip,a); put Edit(quibbling('ABC DEF G H'))(Skip,a); return;
quibbling: proc(s) Returns(Char(100) Var); Dcl s Char(*); Dcl result Char(100) Var; Dcl (wi,p) Bin Fixed(31); If s= Then result=; Else Do; Do wi=1 By 1 While(s^=); p=index(s,' '); If p=0 Then Do; If wi>1 Then result=result!!' and '!!s; else result=s; s=; End; Else Do; If wi=1 Then result=left(s,p-1); Else result=result!!', '!!left(s,p-1); s=substr(s,p+1); End; End; End; Return('{'!!result!!'}'); End; End;</lang>
- Output:
{} {ABC} {ABC, DEF} {ABC, DEF, G, H}
REXX
<lang rexx>say quibbling() say quibbling('ABC') say quibbling('ABC DEF') say quibbling('ABC DEF G H') exit
quibbling: procedure
parse arg list Select When list= Then result= When words(list)=1 then result=word(list,1) Otherwise result=translate(strip(subword(list,1,words(list)-1)),',',' '), 'and' word(list,words(list)) End Return '{'result'}'</lang>
- Output:
{} {ABC} {ABC and DEF} {ABC,DEF,G and H}
Rust
<lang Rust>fn quibble(seq: &[~str]) -> ~str {
match seq { [] => ~"{}", [ref w] => fmt!("{%s}", *w), [..ws, ref w] => fmt!("{%s and %s}", ws.connect(", "), *w), }
}
fn main() {
println(quibble([~"ABC"])); println(quibble([~"ABC", ~"DEF"])); println(quibble([~"ABC", ~"DEF", ~"G", ~"H"]));
}</lang>
- Output:
{ABC} {ABC and DEF} {ABC, DEF, G and H}
Tcl
<lang tcl>proc commaQuibble {lst} {
if {[llength $lst] > 1} {
set lst [lreplace $lst end-1 end [join [lrange $lst end-1 end] " and "]]
} return \{[join $lst ", "]\}
}
foreach input { {} {"ABC"} {"ABC" "DEF"} {"ABC" "DEF" "G" "H"} } {
puts [commaQuibble $input]
}</lang>
- Output:
{} {ABC} {ABC and DEF} {ABC, DEF, G and H}