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Improved pattern-match code and explanation. #12035

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Feb 5, 2014
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Improved pattern-match code and explanation. #12035

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6 changes: 4 additions & 2 deletions src/doc/tutorial.md
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Original file line number Diff line number Diff line change
Expand Up @@ -509,7 +509,7 @@ fn angle(vector: (f64, f64)) -> f64 {
let pi = f64::consts::PI;
match vector {
(0.0, y) if y < 0.0 => 1.5 * pi,
(0.0, y) => 0.5 * pi,
(0.0, _) => 0.5 * pi,
(x, y) => atan(y / x)
}
}
Expand All @@ -519,7 +519,9 @@ A variable name in a pattern matches any value, *and* binds that name
to the value of the matched value inside of the arm's action. Thus, `(0.0,
y)` matches any tuple whose first element is zero, and binds `y` to
the second element. `(x, y)` matches any two-element tuple, and binds both
elements to variables.
elements to variables. `(0.0,_)` matches any tuple whose first element is zero
and does not bind anything to the second element.

A subpattern can also be bound to a variable, using `variable @ pattern`. For
example:

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