Typescript: Object of T but value is Predicate

Question

for the following function (see also http://ramdajs.com/docs/#where)

var spec2 = {x: function(val, obj) { return  val + obj.y > 10; }};
R.where(spec2, {x: 2, y: 7}); //=> false
R.where(spec2, {x: 3, y: 8}); //=> true

I would like to create the typing for the case where the object T has the value of a predicate.

I was thinking I would do something like this:

    where<T>(spec: {item: (val: any, testObj: T) => boolean}, testObj: T): boolean;

but I'm not sure what to do for the key.

Ryan Cavanaugh · Accepted Answer · 2015-04-22 16:38:49Z

2

There isn't a way to represent this in the TypeScript type system.

answered Apr 22, 2015 at 16:38

Ryan Cavanaugh

223k59 gold badges280 silver badges235 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jon49 · Accepted Answer · 2015-04-24 16:07:10Z

0

This seems to get closer to a solution which is partially type safe:

interface Pred2<T> {
    (x: any, y: T): boolean
}
interface ObjPred2<T> {
    [index: string]: Pred2<T>;
}
where<T>(spec: ObjPred2<T>, testObj: T): boolean;

answered Apr 24, 2015 at 16:07

Jon49

4,6164 gold badges41 silver badges78 bronze badges

Collectives™ on Stack Overflow

Typescript: Object of T but value is Predicate

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related