── ✗ missing method ───────────────────────────────────────────────────────────────────────────────── Allergies.roc:29:7

This to_hash call is on a value whose type never resolved to a concrete type, so it has no to_hash method.

d = set(3)
    ^^^

Using the value somewhere that requires a specific type, or annotating it, will give it one.

Allergies :: {}.{
    Allergen : [Eggs, Peanuts, Shellfish, Strawberries, Tomatoes, Chocolate, Pollen, Cats]

    allergic_to : Allergen, U64 -> Bool
    allergic_to = |allergen, score| {
        set(score).contains(allergen)
    }

    set : U64 -> Set(Allergen)
    set = |score| {
        [1, 2, 4, 8, 16, 32, 64, 128].keep_if(|n| score.bitwise_and(n) > 0)
            |> List.map(
                |n| match n {
                    1 => Eggs
                    2 => Peanuts
                    4 => Shellfish
                    8 => Strawberries
                    16 => Tomatoes
                    32 => Chocolate
                    64 => Pollen
                    128 => Cats
                    _ => crash "Invalid score"
                },
            )
            |> Set.from_list()
    }

    expect {
        d = set(3)
        dbg d
        d.contains(Eggs) == Bool.True
    }
}