Duration parser for Options in effect/cli, like config in effect about effect HOT 7 CLOSED

Hey @joepjoosten - I think I'm understanding a bit better now.

First of all, let me clear up that Options is not analagous to a ConfigProvider whatsoever.

Options uses the ConfigProvider to allow the CLI program to fall back to the specified Config value when the command-line flag is not provided. So in a situation where optionA is not provided by the user, it can fall back to the specified Config value, which will be read using whichever ConfigProvider is provided to the program. The default ConfigProvider reads from the environment, so if no ConfigProvider is provided by you in your CLI program the default behavior will be to fall back to the value in the environment (if present).

Also, looking at your sample above, I would adjust the code as follows:

Options.text("optionA").pipe(
  Options.withDescription('Option A.'), 
  Options.withFallbackConfig(Config.string("OPTION_A")),
  Options.optional
)

which moves the Options.optional to the end of the pipeline and removes the Config.option.

This will result in the following behavior when the optionA command-line option attempts to be parsed:

1. Read the command-line and use the specified value, if present, returning Option.some(value)
2. If not, try reading from the environment and use that value, if present, returning Option.some(value)
3. If not, return Option.none

The way you wrote optionA previously, you would never attempt to use the fallback config value since Options.optional would just return Option.none if the command-line value wasn't there.

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Also, regarding parsing a duration from the command line, you could just do:

import * as Options from "@effect/cli/Options"
import * as Duration from "effect/Duration"
import * as Option from "effect/Option"

const myOption = Options.text("optionA").pipe(
  Options.withDescription('Option A.'), 
  Options.withFallbackConfig(Config.string("OPTION_A")),
  Options.optional,
  Options.map(Option.flatMap(Duration.decodeUnknown))
)

Note: I did not test this code in an editor, you might need to adjust slightly.

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A more general question: Options in effect/cli is "closely" related to Config in effect, in other words: is a subset / intersection of the Config methods? Is it possible to reuse this subset / intersection?

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They don't look related imho, Config is a description of a configuration to be read from a ConfigProvider, Options in CLI represent options that the user can pass through cli flags, maybe @IMax153 can shed some further light

from effect.

@joepjoosten - as @mikearnaldi mentioned, I'm not seeing the parallel between Config and Options. They are two totally separate data types used for different purposes.

Are you looking for a way to parse a duration input from the command line?

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@mikearnaldi @IMax153 Good point.

What i noticed when i was writing Options for my CLI the following way:

Options.text("optionA").pipe(
  Options.optional, 
  Options.withDescription('Option A.'), 
  Options.withFallbackConfig(
    Config.string("OPTION_A").pipe(Config.option)
  )
)

That's why it seemed related (in one direction: Config -> Options)

I saw the "inconsistancy" between e.g. Options.optional <=> Config.option, and that Options is lacking the recently added Config.duration.

Maybe the Options are a ConfigProvider in a way?

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Great answer! solves my questions.

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