I'm trying to loop through a mapping list (type_a) and update a different mapping list (type_b). Both lists are different. For List.fold, does the accumulator have to be the same type as list? ie, if we have
let fn = fun (acc, a: type_b * type_a list) : type_b = ...
let my_list : type_a list = Map.literal[...]
let acc : type_b = ...
let sum_of_elements : int = List.fold_left fn acc my_list
Does acc have to be of type_a
? I'm getting a few errors about the fields not matching, but I'm not sure if that is because this is not allowed, or something else..