[英]Typescript doesn't select the correct overload based on callback return type
Given the following code (playground link: http://bit.ly/1n7Fcow ) 给出以下代码(游乐场链接: http : //bit.ly/1n7Fcow )
declare function pick<T, V>(f:(x:T, y:V) => V):V;
declare function pick<T, V>(f:(x:T, y:V) => T):T;
var xx = pick((x: number, y:string) => x);
var yy = pick((x: number, y:string) => y);
TypeScript selects an incorrect overload and fails to infer the type of xx
. TypeScript选择了不正确的重载,无法推断xx
的类型。
Is it possible to make typescript select the right overload there? 是否有可能使打字稿选择正确的超载?
note: to avoid the XY problem, this is the original problem - http://bit.ly/QXaQGc - I need this kind of overloading in order to be able to model promises correctly. 注意:为了避免XY问题,这是最初的问题 - http://bit.ly/QXaQGc - 我需要这种重载才能正确建模promises。
I was able to get the playground to infer the correct type of xx and yy correctly by changing the call to this: 通过更改对此的调用,我能够让操场正确地推断出正确的xx和yy类型:
declare function pick<T, V>( f:(x:T, y:V) => V ):V;
declare function pick<T, V>( f:(x:T, y:V) => T ):T;
var xx = pick<number,string>((x, y) => x);
var yx = pick<number,string>((x, y) => y);
See here: http://bit.ly/1p6h8iP Hope this help. 看到这里: http : //bit.ly/1p6h8iP希望这个帮助。
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