Erlang gen_server implementation - erlang

Question

In the code below, why is the module prime_server not loading?
-module(prime_server).
-behaviour(gen_server).
-export([new_prime/1, start_link/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
new_prime(N) ->
%% 20000 is a timeout (ms)
gen_server:call(?MODULE, {prime, N}, 20000).
init([]) ->
%% Note we must set trap_exit = true if we
%% want terminate/2 to be called when the application
%% is stopped
process_flag(trap_exit, true),
io:format("~p starting~n" ,[?MODULE]),
{ok, 0}.
handle_call({prime, K}, _From, N) ->
{reply, make_new_prime(K), N+1}.
handle_cast(_Msg, N) -> {noreply, N}.
handle_info(_Info, N) -> {noreply, N}.
terminate(_Reason, _N) ->
io:format("~p stopping~n" ,[?MODULE]),
ok.
code_change(_OldVsn, N, _Extra) -> {ok, N}.
make_new_prime(K) ->
if
K > 100 ->
alarm_handler:set_alarm(tooHot),
N = lib_primes:make_prime(K),
alarm_handler:clear_alarm(tooHot),
N;
true ->
lib_primes:make_prime(K)
end.
OUTPUT:
$ erl -boot start_sasl
1>c(prime_server).
{ok,prime_server}
2>c(my_alarm_handler).
my_alarm_handler.erl:2: Warning: undefined callback function code_change/3 (behaviour 'gen_event')
my_alarm_handler.erl:19: Warning: variable 'Reply' is unused
{ok,my_alarm_handler}
3> {ok, Pid} = prime_server:start_link().
prime_server starting
{ok, <0.73.0>}
4> prime_server:new_prime(6).
prime_server stopping
=ERROR REPORT==== 24-Mar-2014::10:59:39 ===
** Generic server prime_server terminating
** Last message in was {prime,6}
** When Server state == 0
** Reason for termination ==
** {'module could not be loaded',
[{lib_primes,make_prime,[6],[]},
{prime_server,handle_call,3,[{file,"prime_server.erl"},{line,21}]},
{gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,585}]},
{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,239}]}]}
=CRASH REPORT==== 24-Mar-2014::10:59:39 ===
crasher:
initial call: prime_server:init/1
pid: <0.73.0>
registered_name: prime_server
exception exit: {undef,
[{lib_primes,make_prime,[6],[]},
{prime_server,handle_call,3,
[{file,"prime_server.erl"},{line,21}]},
{gen_server,handle_msg,5,
[{file,"gen_server.erl"},{line,585}]},
{proc_lib,init_p_do_apply,3,
[{file,"proc_lib.erl"},{line,239}]}]}
in function gen_server:terminate/6 (gen_server.erl, line 744)
ancestors: [<0.71.0>]
messages: []
links: [<0.71.0>]
dictionary: []
trap_exit: true
status: running
heap_size: 610
stack_size: 27
reductions: 181
neighbours:
neighbour: [{pid,<0.71.0>},
{registered_name,[]},
{initial_call,{erlang,apply,2}},
{current_function,{gen,do_call,4}},
{ancestors,[]},
{messages,[]},
{links,[<0.27.0>,<0.73.0>]},
{dictionary,[]},
{trap_exit,false},
{status,waiting},
{heap_size,610},
{stack_size,36},
{reductions,1303}]
** exception exit: undef
in function lib_primes:make_prime/1
called as lib_primes:make_prime(6)
in call from prime_server:handle_call/3 (prime_server.erl, line 21)
in call from gen_server:handle_msg/5 (gen_server.erl, line 585)
in call from proc_lib:init_p_do_apply/3 (proc_lib.erl, line 239)
9> gen_server:call(prime_server, 6).
** exception exit: {noproc,{gen_server,call,[prime_server,6]}}
in function gen_server:call/2 (gen_server.erl, line 180)
10> gen_server:call(prime_server, new_prime, 6).
** exception exit: {noproc,{gen_server,call,[prime_server,new_prime,6]}}
in function gen_server:call/3 (gen_server.erl, line 188)
11> gen_server:call(prime_server, new_prime(5), []).
** exception error: undefined shell command new_prime/1
12> gen_server:call(prime_server, {prime, 4}, []).
** exception exit: {{function_clause,
[{gen,call,
[prime_server,'$gen_call',{prime,4},[]],
[{file,"gen.erl"},{line,147}]},
{gen_server,call,3,
[{file,"gen_server.erl"},{line,184}]},
{erl_eval,do_apply,6,
[{file,"erl_eval.erl"},{line,573}]},
{shell,exprs,7,[{file,"shell.erl"},{line,674}]},
{shell,eval_exprs,7,[{file,"shell.erl"},{line,629}]},
{shell,eval_loop,3,[{file,"shell.erl"},{line,614}]}]},
{gen_server,call,[prime_server,{prime,4},[]]}}

Answer 1

{'module could not be loaded',
[{lib_primes,make_prime,[6],[]},
{prime_server,handle_call,3,[{file,"prime_server.erl"},{line,21}]},
{gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,585}]},
{proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,239}]}]}
From the log, you use this module lib_primes, do you have this file lib_primes.erl?
I think you should compiule and load this module lib_primes first.