Linq request: Match method

[simon-curtis]

Simple proposal to return both matched and unmatched results from a where query in a one-liner.

var chars = new char[] { 'a', 'b', 'c' };

(matched, unmatched) = chars.Match(c => c == 'a');
for (var element in unmatched) ...

//or

IMatchResults results = chars.Match(c => c == 'a');
for (var element in results.Unmatched) ...

For readability I would normally do the following; but requires and extra pass

var chars = new char[] { 'a', 'b', 'c' };
var matched = chars.Where(c => c == 'a');
var unmatched = chars.Where(c => c != 'a');

You can achieve this in one pass using a for loop, but goes against the point of Linq and is longer

var chars = new char[] { 'a', 'b', 'c' };
var matched = new List<char>();
var unmatched = new List<char>();
foreach (var c in chars) {
    if (c == 'a') {
        matched.Add(c);
    } else {
        unmatched.Add(c);
    }
}

[333fred]

Closing out. Already moved this to the right repo.

[jnm2]

Moved to dotnet/runtime#39443