Erlang utilities. Concatenates mixed list of values (binaries/strings/atom/integer/float) into a single binary or string.

utils.erl

-module(utils).

-export([concat/2]).

%% EXTERNAL

concat(Words, string) ->
    internal_concat(Words);
concat(Words, binary) ->
    list_to_binary(internal_concat(Words)).

%% INTERNAL

internal_concat(Elements) ->
    NonBinaryElements = [case Element of _ when is_binary(Element) -> binary_to_list(Element); _ -> Element end || Element <- Elements],
    lists:concat(NonBinaryElements).

%% EUNIT TESTS

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

concat_conversion_test_() ->
    [
        {"list of strings to string", ?_assertEqual("This and that.", utils:concat(["This", " and", " that."], string))},
        {"list of strings to binary", ?_assertEqual(<<"This and that.">>, utils:concat(["This", " and", " that."], binary))},
        {"list of binaries to string", ?_assertEqual("This and that.", utils:concat([<<"This">>, <<" and">>, <<" that.">>], string))},
        {"list of binaries to binary", ?_assertEqual(<<"This and that.">>, utils:concat([<<"This">>, <<" and">>, <<" that.">>], binary))},
        {"mix of values to string", ?_assertEqual("This and that 5asdf hi.", utils:concat([<<"This">>, " and", <<" that ">>, 5, asdf, " hi."], string))},
        {"mix of values to binary", ?_assertEqual(<<"This and that 5asdf hi.">>, utils:concat([<<"This">>, " and", <<" that ">>, 5, asdf, " hi."], binary))}
    ].