[Question] is there any better way to combine two Reader<Deps1, Result1> and Reader<Deps2, Result2>?

[apiep]

So, I have a function that return Reader<Deps1, Task<bool>> called waitForAuthenticated() and a second function that return Reader<Deps2, Task<R>> called getSomething(), is there a better way to compose both reader?

I have tried to use

var task1 = waitForAuthenticated().run(_deps1);
var task2 = getSomething().run(_deps2);

// ...
// At the outside part of my code / public facing API
task1(task2).run();

But then, I kind of "dislike" calling .run() method on reader as it make my reader not lazy now, is there a better way to do this without calling .run() method on my reader?

[SandroMaglione]

Hi @apiep

Am I correct in assuming that you just want to execute task1 and task2 one after the other, without dependencies between the two?

In that case you can use local to change the context from Deps1 to Deps2:

import 'package:fpdart/fpdart.dart';

class Deps1 {
  final String dep;
  const Deps1(this.dep);
}

class Deps2 {
  final String dep;
  const Deps2(this.dep);
}

Reader<Deps1, Task<bool>> waitForAuthenticated() => Reader(
      (deps1) {
        print('Execute waitForAuthenticated: ${deps1.dep}');
        return Task.of(true);
      },
    );

Reader<Deps2, Task<String>> getSomething() => Reader(
      (deps2) {
        print('Execute getSomething: ${deps2.dep}');
        return Task.of("");
      },
    );

void main() async {
  const _deps1 = Deps1('I am Deps1');
  const _deps2 = Deps2('I am Deps2');
  final pipe = waitForAuthenticated()
      .local<Deps2>(constF(_deps1))
      .andThen(getSomething)
      .run(_deps2);

  final result = await pipe.run();
}

This code chains the calls to waitForAuthenticated and getSomething by calling them one after the other. The result is the following:

Execute waitForAuthenticated: I am Deps1
Execute getSomething: I am Deps2

Is this what you where looking for?

[apiep]

Yes it is something like that, that I wanted. Thank you :)

I noticed local method before, but because it has a parameter with it, that's the part what confuse me