haxe“应该是int"错误 [英] haxe "should be int" error

问题描述

假冒似乎认为某些东西必须是Int.在以下功能中，

Haxe seems to assume that certain things must be Int. In the following function,

class Main {
    static function main() {
        function mult_s<T,A>(s:T,x:A):A { return cast s*x; }
        var bb = mult_s(1.1,2.2);
    }
}

我得到了(使用Haxe 3.01):

I got (with Haxe 3.01):

Main.hx:xx: characters 48-49 : mult_s.T should be Int
Main.hx:xx: characters 50-51 : mult_s.A should be Int

任何人都可以解释为什么T和A应该是Int而不是Float吗?

Can anyone please explain why T and A should be Int instead of Float?

另一个令人困惑的例子是

A more puzzling example is this:

class Main {
    public static function min<T:(Int,Float)>(t:T, t2:T):T { return t < t2 ? t : t2; }
    static function main() {
        var a = min(1.1,2.2); //compile error
        var b = min(1,2); //ok
    }
}

我不明白为什么t<t2暗示t或t2是Int.但是Haxe似乎更喜欢Int:如果使用Int进行调用，则min很好，但是如果使用Float进行调用，则失败.这合理吗?

I can't see why t<t2 implies that either t or t2 is Int. But Haxe seems prefer Int: min is fine if called with Int's but fails if called with Float's. Is this reasonable?

谢谢

推荐答案

min<T:(Int,Float)>表示T应该同时为 和Int 和 Float.请参阅Haxe手册的约束部分. .

min<T:(Int,Float)> means T should be both Int and Float. See the constraints section of Haxe Manual.

鉴于Int可以隐式转换为Float，您可以安全地删除Int的约束.即以下方法将起作用:

Given Int can be converted to Float implicitly, you can safely remove the constraint of Int. i.e. the following will works:

http://try.haxe.org/#420bC

class Test {
  public static function min<T:Float>(t:T, t2:T):T { return t < t2 ? t : t2; }
  static function main() {
    var a = min(1.1,2.2); //ok
    $type(a); //Float
    trace(a); //1.1
    var b = min(1,2); //ok
    $type(b); //Int
    trace(b); //1
  }
}

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