src/hyper_array.erl

-module(hyper_array).
-export([new/1, get/2, set/3, fold/3, max_merge/2]).
-behaviour(hyper_register).

new(P) ->
    M = trunc(math:pow(2, P)),
    array:new([{size, M}, {fixed, true}, {default, 0}]).

get(Index, A) ->
    case array:get(Index, A) of
        0 ->
            undefined;
        Value ->
            {ok, Value}
    end.


set(Index, Value, A) ->
    array:set(Index, Value, A).

fold(F, Acc, A) ->
    array:sparse_foldl(F, Acc, A).

max_merge(Left, Right) ->
    fold(fun (Index, L, Registers) ->
                 case get(Index, Registers) of
                     {ok, R} when R < L ->
                         set(Index, L, Registers);
                     {ok, _} ->
                         Registers;
                     undefined ->
                         set(Index, L, Registers)
                 end
         end, Right, Left).