Erlang: Pretty print nested dictionaries

prettyprintdict.erl

%% @author Hunter Wilhelm
-module(prettyprintdict).
-export([pretty_print_dictionary/1]).

%%%--------
%%% helper functions
%%%--------

%% @doc The <kbd>isdict/1</kbd> function is a helper function that returns true if the
%% parameter is a dictionary. This function might not work in future updates of erlang if they
%% change how a dictionary is represented internally.
isdict(DictCand) when is_tuple(DictCand) andalso element(1, DictCand) =:= dict ->
    true;
isdict(_NotDict) ->
    false.

%%%--------
%%% print functions
%%%--------

%% @doc The <kbd>pretty_print_entries/2</kbd> function prints out the values of 
%% the list if they are not dictionaries, otherwise, it increases the 
%% indentation and pretty prints the sub dictionary.
pretty_print_entries([], _) -> ok;
pretty_print_entries([{Key, Value} | Entries], Indentation) ->
    case is_atom(Key) of
        true -> io:format("~s~p~n", [["| " || _ <- lists:seq(1, Indentation)], Key]);
        _ -> io:format("~s~s~n", [["| " || _ <- lists:seq(1, Indentation)], [Key]])
    end,
    case isdict(Value) of
        true -> pretty_print_dictionary(Value, Indentation + 1);
        false -> io:format("~s~p~n", [["|-" || _ <- lists:seq(1, Indentation + 1)], Value])
    end,
    pretty_print_entries(Entries, Indentation).

%% @doc The <kbd>pretty_print_dictionary/2</kbd> function pretty prints a dictionary.
pretty_print_dictionary(Dict, Indentation) ->
    Entries = dict:to_list(Dict),
    pretty_print_entries(Entries, Indentation).

%%%--------
%%% facade/public functions
%%%--------

%% @doc The <kbd>pretty_print_dictionary/1</kbd> function pretty prints a dictionary.
pretty_print_dictionary(Dict) ->
    pretty_print_dictionary(Dict, 0).