[swift-evolution] Extending the for loop to have multiple clauses

[J. Cheyo Jimenez]

The proposed extension looks to me like is iterating both the suits and
rank at the same time. In that case I think is a great idea.

var cards: [(Suit,Rank)] = []
for x in suits, y in ranks {
  cards.append((x,y))
}

What I am expecting:

x1, y1
x2, y2
x3, y3
etc

This reminds me that this is one of the ways I use the C-style for-loop.
The alternative now:

for (index, x) in suits.enumerate(){
   let y = ranks[index]
   cards.append((x,y))

}






On Wed, Dec 9, 2015 at 12:00 PM, Chris Eidhof via swift-evolution <
swift-evolution at swift.org> wrote:

> I think it could be really nice to extend the for-loop so that it can have
> multiple clauses. Much like in the if-let with multiple clauses, I could
> imagine a for-loop with multiple clauses:
>
> var cards: [(Suit,Rank)] = []
> for x in suits, y in ranks {
>   cards.append((x,y))
> }
>
> This would be the same as writing:
>
> var cards: [(Suit,Rank)] = []
> for x in suits {
>   for y in ranks {
>     cards.append((x,y))}
>   }
> }
>
> You could also do something like:
>
> for x in input1, y in (x..<end) {
>    // Do something with (x,y)
> }
>
> In fact, once we would have that, we could combine both if-let and for,
> and make it more general, to end up with something like Haskell’s
> do-notation or C#’s LINQ. But that might be taking it too far...
>
> Chris
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