diegonc

local function pbOrderedEncode(type, data)
    -- Check type
    if pb.type(type) == nil then
        return nil, string.format("type '%s' does not exists", type)
    end
    -- List type fields
    local typeFields = {}
    for name, number, type, defval, flags in pb.fields(type) do
        typeFields[name] = {
            name = name,

diegonc

Say there's an l of type List a, an e of type b which represent an empty collection and a function add of type a -> b -> Result x b.

add inserts an a into a b which is an operation that could fail.

I'd like to apply a fold through l using add as the reducer so that in the end I have a Result with either the b that contains all of the as in the list or an error.

However, I can't just do List.foldl add e l because of the signature of add.