Effect CommunityEC
Effect Community•14mo ago
Viridian

Using Effect.filterOrElse to handle conditional logic can be a bit tricky, especially when you wa...

I've been working on some Effect code for AOC day 3:

const checkState = (state: State, instruction: string) => pipe(
    instruction,
    Effect.succeed,
    Effect.flatMap(instr =>
        Match.value(instr).pipe(
            Match.when("do()", () => {
                console.log("Enabling multiplications")
                return Effect.succeed({ ...state, enabled: true })
            }),
            Match.when("don't()", () => {
                console.log("Disabling multiplications")
                return Effect.succeed({ ...state, enabled: false })
            }),
            Match.orElse(() => {
                if (!state.enabled) {
                    console.log(`Skipping disabled multiplication: ${instruction}`)
                    return Effect.succeed(state)
                }
                const newState = parseInput(state, instruction)
                console.log(`Processing ${instruction}: ${state.sum} -> ${newState.sum}`)
                return Effect.succeed(newState)
            })
        )
    )
)


I'm trying to make the code in the orElse block more effectful. I was trying to do it with something like this:

Match.orElse(() =>
                pipe(
                    Effect.succeed(state),
                    Effect.filterOrElse(
                        s => s.enabled,
                        () => Effect.succeed(state),
                    ),
                    Effect.map(() => parseInput(state, instr)),
                )
            )


But that doesn't match the output properly. Any clue on what direction I should be looking at?
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