Created
March 18, 2014 17:02
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| // these two are taken from the docs | |
| struct Point { | |
| x: f64, | |
| y: f64 | |
| } | |
| // They use shape later in the docs to show pattern matching | |
| // but I'm going to attempt to explain it | |
| // In the parens you are declaring list of types that variant makes | |
| // up essentially. So Circle defines a Point (center), Float (Radius) | |
| // Rectange is Point (top left) and Point (bottom right) | |
| enum Shape { | |
| Circle(Point, f64), | |
| Rectangle(Point, Point) | |
| } | |
| // Now lets say we do this | |
| let a: Shape = Circle(Point { x: 12, y: 10}, 6.0); | |
| let b: Shape = Rectange(Point { x: 5, y: 5 }, Point { x: 10, y: 10 }); | |
| // match detructures shape so you can use the value | |
| // also notice how the variables are pulled out of it as well. | |
| fn area(s: Shape) { | |
| match s { | |
| Circle(c, r) => ..., | |
| Rectangle(tr, bl) => ... | |
| } | |
| } | |
| /* | |
| as a side not the { } operator is interesting it's an expression and the last thing | |
| evaluated without a semicolon is the return value if a the satement has a semicolon | |
| then the expression returns the unit value of () | |
| so | |
| { | |
| let x = 4; | |
| x | |
| } | |
| returns 4 | |
| where as | |
| { | |
| let x = 4; | |
| x; | |
| } | |
| returns () | |
| there is a return statement but is generally considered bad practice to use (per docs) unless | |
| you are trying to exit early. | |
| /* |
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