Merge pull request #1243 from fabiopakk/patch-1

More precise wording regarding 'pairs' example

Author: SethTisue

_tour/for-comprehensions.md

@@ -37,19 +37,19 @@ Here is a more complicated example using two generators. It computes all pairs o
 ```tut
 def foo(n: Int, v: Int) =
    for (i <- 0 until n;
-        j <- i until n if i + j == v)
+        j <- 0 until n if i + j == v)
    yield (i, j)
 
 foo(10, 10) foreach {
   case (i, j) =>
-    println(s"($i, $j) ")  // prints (1, 9) (2, 8) (3, 7) (4, 6) (5, 5)
+    println(s"($i, $j) ")  // prints (1, 9) (2, 8) (3, 7) (4, 6) (5, 5) (6, 4) (7, 3) (8, 2) (9, 1)
 }
 
 ```
 Here `n == 10` and `v == 10`. On the first iteration, `i == 0` and `j == 0` so `i + j != v` and therefore nothing is yielded. `j` gets incremented 9 more times before `i` gets incremented to `1`. Without the `if` guard, this would simply print the following:
 ```
 
-(0, 0) (0, 1) (0, 2) (0, 3) (0, 4) (0, 5) (0, 6) (0, 7) (0, 8) (0, 9) (1, 1) ...
+(0, 0) (0, 1) (0, 2) (0, 3) (0, 4) (0, 5) (0, 6) (0, 7) (0, 8) (0, 9) (1, 0) ...
 ```
 
 Note that comprehensions are not restricted to lists. Every datatype that supports the operations `withFilter`, `map`, and `flatMap` (with the proper types) can be used in sequence comprehensions.
@@ -59,7 +59,7 @@ You can omit `yield` in a comprehension. In that case, comprehension will return
 ```tut
 def foo(n: Int, v: Int) =
    for (i <- 0 until n;
-        j <- i until n if i + j == v)
+        j <- 0 until n if i + j == v)
    println(s"($i, $j)")
 
 foo(10, 10)