Add Option.mapEffect for better native interoperability between Option and Effect.

[anglinb]

What is the problem this feature would solve?

I frequently want to take an option like Option.Option<number> and apply some effect to the result to turn that option into Option.Option<Effect.Effect<Something>> but the options to do so feel really clunky in comparison to a simple Option.mapEffect call.

Here's a breakdown of the existing ways I've tried to solve the issue: https://effect.website/play#be67835bcf4d

What is the feature you are proposing to solve the problem?

My proposed solution would look like this:

// Proposed new implementation
const mapEffect = <Value, S, F, C>(
  option: Option.Option<Value>,
  effect: (some: Value) => Effect.Effect<S, F, C>
): Effect.Effect<Option.Option<S>, F, C> => {
  return Option.match(option, {
    onSome: (some) =>
      effect(some).pipe(
        Effect.map((s) => Option.some(s))
      ),
    onNone: () => Effect.succeed(Option.none<S>()) as Effect.Effect<Option.None<S>, F, C>
  })
}

Here's a full example: https://effect.website/play#be67835bcf4d

What alternatives have you considered?

I've tried unwrapping the option and catching and now using Effect.transposeOption but I still think this simple api would make for a much nicer one-liner for dealing with this situation.

[gcanti]

I think Effect.transposeOption should be sufficient, as mapEffect is essentially just Option.map combined with transposeOption:

import { Effect, Option } from "effect"

const mapEffect = <Value, S, F, C>(
  option: Option.Option<Value>,
  f: (some: Value) => Effect.Effect<S, F, C>
) => {
  return option.pipe(
    Option.map(f),
    Effect.transposeOption
  )
}

[anglinb]

I agree, was just hoping to combine those two lines into one API since 1) I use it very frequently and 2) to improve discoverability.