Haxe中的一个块由一个开口的 花括号 { 开始，以一个闭口的花括号 }结束。一个块可以包含一些表达式，每个使用分号结束。通常的语法是： > A block in Haxe starts with an opening curly brace { and ends with a closing curly brace }. A block may contain several expressions, each of which is followed by a semicolon ;. The general syntax is thus: ~~~ { expr1; expr2; ... exprN; } ~~~ 值和被块表达式扩展的类型等于值和最后一个子表达式的类型。 > The value and by extension the type of a block-expression is equal to the value and the type of the last sub-expression. 块可以包含局部变量，通过 var表达式（第5.10节）声明，同样，局部函数通过 function 表达式（第5.11节）声明。它们在块和子块中中是可用的，但是不能在块的范围之外使用。同样，只有在被声明之后才可以使用。下面的例子使用 var，但是同样个规则应用到 function的用法： > Blocks can contain local variables declared by var expression (5.10), as well as local functions declared by function expressions (5.11). These are available within the block and within sub-blocks, but not outside the block. Also, they are available only after their declaration. The following example uses var, but the same rules apply to function usage: ~~~ { a; // error, a is not declared yet var a = 1; // declare a a; // ok, a was declared { a; // ok, a is available in sub-blocks } // ok, a is still available after // sub-blocks a; } a; // error, a is not available outside ~~~ 在运行时，块从头至尾执行。控制流（如异常（第5.18节）或者返回表达式（第5.19节））可能在所有的表达式被执行之前离开块。 > At runtime, blocks are evaluated from top to bottom. Control flow (e.g. exceptions (5.18) or return expressions (5.19)) may leave a block before all expressions are evaluated.