Bug 12106 – Formatting syntax for a range of typecons tuples

This is a syntax to format the key and values of an associative array: import std.stdio: writefln; void main() { auto aa = [1: 10, 2: 20, 3: 30]; writefln("%(%d: %d\n%)", aa); } Its output: 1: 10 2: 20 3: 30 I'd often like to format in a similar way a range of std.typecons.Tuple, using some syntax: import std.stdio: writefln; import std.range: zip; void main() { auto r1 = zip([1, 2, 3], [10, 20, 30]); writefln("%(%d: %d\n%)", r1); auto r2 = zip([1, 2, 3], [10, 20, 30], [100, 200, 300]); writefln("%(%d: %d, %d\n%)", r2); } Such ranges of tuples are rather common, they are generated by zip() and group() and other Phobos functions, and in future by the enumerate() function (Issue 5550 ) and AA.byPair (Issue 5466 ) too. Here I have used a syntax similar to the associative array one. If you use only one formatting % then it formats the whole tuple, otherwise it requires as many % as the fields of the tuple, not one more not one less. Unfortunately this simple syntax is ambiguous when you have a range of 1-tuples: import std.stdio: writefln; import std.range: zip; void main() { auto r0 = zip([10, 20, 30]); writefln("%(%s\n%)", r0); } Currently this works and outputs: Tuple!int(10) Tuple!int(20) Tuple!int(30) So this whole idea seems to need a way to disambiguate this case. Ideas are welcome.

Fixed by: https://github.com/D-Programming-Language/phobos/pull/3833