erlang_fizzbuzz_kata.erl

-module(fizzbuzz).
-export([evaluateV1/1]).
-export([evaluateV2/1]).
-export([evaluateV3/1]).
-export([evaluateV4/1]).

-include_lib("eunit/include/eunit.hrl").

divisorToWordMap() ->
    #{
        3 => "fizz",
        5 => "buzz",
        7 => "bazz"
    }.


%%%%%% V4 %%%%%%
evaluateV4(Number) ->
    case lists:concat(
        lists:map(fun({Divisor, Word}) ->
            case Number rem Divisor of
                0 -> Word;
                _ -> ""
            end
        end, maps:to_list(divisorToWordMap()))
    ) of
        "" -> integer_to_list(Number);
        Concat -> Concat
    end.


%%%%%% V3 %%%%%%
evaluateV3({Number, List}) when 1 =:= length(List) ->
    [Head | _Tail] = List,
    wordForNumber(Number, Head);
evaluateV3({Number, List}) ->
    [Head | Tail] = List,
    string:concat(wordForNumber(Number, Head), evaluateV3({Number, Tail}));
evaluateV3(Number) ->
    case evaluateV3({Number, maps:to_list(divisorToWordMap())}) of
        "" -> integer_to_list(Number);
        Result -> Result
    end.


wordForNumber(Number, {Divisor, Word}) when 0 =:= Number rem Divisor ->
    Word;
wordForNumber(_Number, {_Divisor, _Word}) ->
    "".



%% Test %%

evaluate_with_a_number_that_not_match_any_rules_returns_number_itself_test() ->
    ?assertEqual("2", evaluateV4(2)).

evaluate_with_a_multiple_of_three_returns_fizz_test() ->
    ?assertEqual("fizz", evaluateV4(6)).

evaluate_with_a_multiple_of_five_returns_buzz_test() ->
    ?assertEqual("buzz", evaluateV4(5)).

evaluate_with_a_multiple_of_three_and_five_returns_fizzbuzz_test() ->
    ?assertEqual("fizzbuzz", evaluateV4(15)).

evaluate_with_a_multiple_of_three_and_seven_returns_fizzbazz_test() ->
    ?assertEqual("fizzbazz", evaluateV4(21)).

evaluate_with_a_multiple_of_three_and_five_and_seven_returns_fizzbuzzbazz_test() ->
    ?assertEqual("fizzbuzzbazz", evaluateV4(105)).


%%%%%% V1 %%%%%%
%%%%% UGLY %%%%%
evaluateV1(NUM) when 0 =:= NUM rem 15 ->
    "fizzbuzz";
evaluateV1(NUM) when 0 =:= NUM rem 5 ->
    "buzz";
evaluateV1(NUM) when 0 =:= NUM rem 3 ->
    "fizz";
evaluateV1(NUM) ->
    integer_to_list(NUM).


%%%%%% V2 %%%%%%
%%%%% UGLY %%%%%
evaluateV2(NUM) ->
    Y = case {NUM rem 3, NUM rem 5} of
        { 0, 0 } -> "fizzbuzz";
        { 0, _ } -> "fizz";
        { _, 0 } -> "buzz";
        { _, _ } -> integer_to_list(NUM)
    end,
    Y.

try with List Comprehensions