Redux saga use Call effect with generic function type typescript

Question

I'm currently using Redux-saga and typescript. But I don't know how to use call effect with generic function type in Typescript.

For eg. I have a function with generic type like this:

function identity<T>(arg: T): T {
    return arg;
}

And, in saga, I expect the code like this:

...
const result = yield call(identity<string>, "myString")
...

However the compiler shows errors. Of course, I can write

const result = yield call(identity, "myString")

But it's not my expectation. How can I know is there any way/syntax to satisfies my above expectation?

Answer 1

Possible solution is to define type of identity function and use it to specialize call invocation.

type identityFunction<T> = (agr: T) => T;

And provide type to call function

yield call<identityFunction<string>>(identity, 'myString');

Now, if you try to call yield call<identityFunction<string>> with wrong arguments (also if signature of identity function will not match type identityFunction<T>), TypeScript will display error.