I am trying to use in Erlang module a beam-file compiled from Elixir source. It raises error when I run Erlang node but I can use the code directly from Elixir.
Elixir module:
defmodule Recursion do
def print_multiple_times(msg, n) when n <= 1 do
IO.puts msg
end
def print_multiple_times(msg, n) do
IO.puts msg
print_multiple_times(msg, n - 1)
end
end
Erlang module:
-module(use_recur).
-define(elixir__recursion, 'Elixir.Recursion').
-export([hey/0]).
hey() ->
?elixir__recursion:print_multiple_times("Hello!", 3).
Compile both:
$ rm -f *.beam
$ elixirc recursion.ex
$ erlc use_recur.erl
Run Erlang:
$ erl -run use_recur hey -run init stop -noshell {"init terminating in do_boot",{undef,[{'Elixir.IO',puts,["Hello!"],[]},{'Elixir.Recursion',print_multiple_times,2,[{file,"recursion.ex"},{line,7}]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({undef,[{Elixir.IO,puts,Hello!,[]},{Elixir.Recursion,print_multiple_times,2,[{},{}]},{init,start_em,1,[]},{init,do_boot,3,[]}]})
Crash dump is being written to: erl_crash.dump...done
Elixir script:
Recursion.print_multiple_times "Hello!", 3
Runs successfully:
$ elixir elx_recur.exs
Hello!
Hello!
Hello!
Why does it happen? I'd say Erlang's output should be the same.
The error means that Erlang could not find a module named 'Elixir.IO'. This module is part of core Elixir. You'll need to add the ebin folder of your Elixir installation to Erlang's load path using -pa (or other similar flags like -pz) to make Erlang load Elixir's core libraries, as that folder contains the compiled .beam files of Elixir core, including Elixir.IO.beam.
erl -pa /path/to/elixir/ebin ...
Related
I have the following Erlang code:
#!/usr/bin/env escript
%%! -pz ../deps/amqp_client ../deps/rabbit_common ../deps/amqp_client/ebin ../deps/rabbit_common/ebin
% RMQ module
-module(rmq).
-export([main/1, send/1, validate/0, test/0]).
-include_lib("../deps/amqp_client/include/amqp_client.hrl").
main(_) ->
%send(<<"test_esio">>),
%validate(),
Pid = spawn(rmq, test, []),
% Pid = spawn(fun() -> test() end), <= I've tried this way too
Pid ! s.
test() ->
receive
s ->
io:format("BAR ~n"),
send(<<"esio">>),
test();
get ->
validate(),
test();
_ ->
io:format("FOO"),
test()
end.
I run this with:
excript rmq.erl
This code doesn't work. Looks like spawn doesn't work.
Rest of my code works, function send and validate works correctly if I run it from main (I've commented its). What I'm doing wrong?
Sorry, maybe it's a dumb question but I'm a beginner with erlang. I've tried search answer in internet and books and I failed...
The problem is not actually in spawn, but in module/escript confusion.
In few words, escript file are not really modules, not from point of Erlang VM, even if you use -module() directive. They are interpreted, and not compiled at all, and definitely they can not be called by module like "rmq:test()", or in you case trough dynamic module call by spawn.
Easiest solution is separate script from actual modules. In your rmq.es you would just start some proper module:
#!/usr/bin/env escript
%%! -pz ../deps/amqp_client ../deps/rabbit_common ../deps/amqp_client/ebin ../deps/rabbit_common/ebin
main(_) ->
rmq:start().
And there in module rmq.erl:
-module(rmq).
-export([start/0, send/1, validate/0, test/0]).
-include_lib("../deps/amqp_client/include/amqp_client.hrl").
start() ->
Pid = spawn(rmq, test, []),
%% Pid = spawn(?MODULE, test, []), %% works with macro too
%% Pid = spawn(fun() -> test() end), <= I've tried this way too
Pid ! s.
test() ->
receive
s ->
io:format("BAR ~n"),
send(<<"esio">>),
test();
get ->
validate(),
test();
_ ->
io:format("FOO"),
test()
end.
Or you could just start this module without escript, with -run flag like this
erl -pz deps/*/ebin -run rmq start
EDIT regarding compilation problems
You compile your modules with erlc command. To just compile use erlc rmq.erl, which will produce rmq.beam file in current directory. But convention is to keep all your source files in src directory, all compiled files in ebin direcory, and things like run-scripts could be placed in the top directory. Something like that:
project
|-- ebin
| |-- rmq.beam
|
|-- src
| |-- rmq.erl
|
|-- rmq.es
Assuming that you run all your shell commands form project directory, to compile all file from src and place .beam binaries in ebin use erlc src/rmq.erl -o ebin, or erlc src/* -o ebin In documentation you can find you explanation of -o flag"
-o directory
The directory where the compiler should place the output files. If not specified, output files will be placed in the current working directory.
Then, after compilation you can run your code, either with erl Erlang VM or using escript (which kind-off uses erl.
erl to runs code from compiled modules, and to do that he needs to be able to locate those compiled *.ebin binaries. For this he uses code path, which is the list of directors in which he will search for those files. This list automatically consist standard library directories, and of course you can add to it directories with your own code with use of -pa flag.
-pa Dir1 Dir2 ...
Adds the specified directories to the beginning of the code path, similar to code:add_pathsa/1. See code(3). As an alternative to -pa, if several directories are to be prepended to the code and the directories have a common parent directory, that parent directory could be specified in the ERL_LIBS environment variable. See code(3).
In your case it would be erl -pa ebin, or to include binaries of all deps you can use erl -pa ebin -pa deps/*/ebin.
Exactly same options are used in second line of your escript. With exception of * character, which will not be expand like it would be in the shell. In escript you have to provide paths to each dependency separately. But the idea of including -pa ebin stays exactly the same.
To automate and standardize this process tools like rebar and erlang.mk where created (I would recommend the later). Using those should help you a little with your workflow.
I am new to Erlang world and currently can't figure out how to start my dummy erlang application. Probably, I am just missing something... So, I created an application with rebar (rebar create-app appid=dummys).
Currently I have
rebar.config
src/dummys.app.src
src/dummys_app.erl
src/dummys_sup.erl
I have found that in order to run an application during a development it is better to create an additional start method which should call application:start(module).
I added some basic logging to my start methods..
start() ->
error_logger:info_msg("Starting app(dev)..~n"),
application:start(dummys_app).
start(_StartType, _StartArgs) ->
error_logger:info_msg("Starting app..~n"),
dummys_sup:start_link().
If I try
erl -noshell -pa ebin -s application start dummys
erl -noshell -pa ebin -s application start dummys_app
there are no output..
If I try
erl -noshell -pa ebin -s dummys start
erl crashes with an error..
If I try
erl -noshell -pa ebin -s dummys_app start
it outputs just "Starting app(dev).." and that's all. But I also expect to see "Starting app.."
What I am missing or doing wrong??
=============
And another question: How to add a new module to my dummy application correctly? For example I have an additional module called "*dummys_cool*" which has a "start" method. How to tell my application to run that "dummys_cool#start" method?
Thank you!
For quick development, if you just want to ensure your appliction can start, start a shell, then start the application:
erl -pa ebin
1> dummys_app:start().
That will give you a clean indication of what is wrong and right without the shell bombing out after.
Since you're making an application to run, rather than just a library to share, you'll want to make a release. Rebar can get you most of the way there:
mkdir rel
cd rel
rebar create-node nodeid=dummysnode
After you've compiled your application, you can create a release:
rebar generate
This will build a portable release which includes all the required libraries and even the erlang runtime system. This is put by default in the rel/ directory; in your case rel/dummys.
Within that directory there will be a control script that you can use to start, stop, and attach to the application:
rel/dummys/bin/dummys start
rel/dummys/bin/dummys stop
rel/dummys/bin/dummys start
rel/dummys/bin/dummys attach
Have a look at your dummys.app.src file. The meaning of all the directives is explained in the 'app' manpage, but the one I suspect is missing here is mod, which indicates the name of your application callback module. So make sure that this line is present:
{mod, {dummys_app, []}}
The empty list in there will be passed as the StartArgs argument to dummys_app:start/2.
To make a new module start along with your application, add it to the supervision tree in dummys_sup:init. This function should look something like:
init(_) ->
{ok, {{one_for_one, 10, 10},
[{dummys_cool, {dummys_cool, start_link, []},
permanent, brutal_kill, worker, [dummys_cool]}]}.
This is described in the 'supervisor' manpage, but basically this means that on startup, this supervisor will start one child process. dummys_cool:start_link() will be called, and that function is expected to spawn a new process, link to it, and return its process id. If you need more processes, just add more child specifications to the list.
erl -noshell -pa ebin -s application start dummys
The code above will not work because application:start([dummys]) will be called.
You can take a reference of the Erlang documentation for details.
For your case,
erl -noshell -pa ebin -s dummys
I ran into this problem, and this was the first answer on Google.
If you are using rebar3, the standard configuration will have a shell command that compiles your project and opens a shell:
$ rebar3 shell
===> Analyzing applications...
===> Compiling myapp
Erlang/OTP 21 [erts-10.2.4] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1]
Eshell V10.2.4 (abort with ^G)
1> ===> Booted myapp
I wanted to run the following eunit test command from console
eunit:test([test_module, [verbose]).
I tried this, but seems not working
erl -noshell -pa ./ebin -s eunit test test_module verbose -init stop
~/uid_server$erl -noshell -pa ./ebin -s eunit test test_module verbose -init stop
undefined
*** test module not found ***
::test_module
=======================================================
Failed: 0. Skipped: 0. Passed: 0.
One or more tests were cancelled.
Do you know how to pass not a simple arguments properly from console?
Your parameters look wrong. This should work:
erl -noshell -pa ebin -eval "eunit:test(test_module, [verbose])" -s init stop
-s can only run functions without arguments by specifying the module and function name (for example init and stop to execute init:stop()).
You can also pass one list to a function of arity 1 like this:
-s foo bar a b c
would call
foo:bar([a,b,c])
All the parameters are passed as a list of atoms only (even when you try to use some other characters, such as numbers, they are converted to atoms).
So since you want to pass two params and not only atoms if you want to run eunit:test/2 you'd have to use -eval which takes a string containing Erlang code as an argument. All -eval and -s functions are executed sequentially in the order they are defined.
Also, make sure you have your test code in ./ebin as well (otherwise write -pa ebin test_ebin where test_ebin is where your test code is).
You can also use rebar...
Get rebar by cd'ing to your project directory and typing the following:
curl http://cloud.github.com/downloads/basho/rebar/rebar -o rebar
chmod u+x rebar
Add the following to your module under test, right after last export:
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-endif.
Next, add your tests at the bottom of your module, wrapped in an ifdef like so:
-ifdef(TEST).
simple_test() ->
?assertNot(true).
-endif.
Lastly, run rebar from your shell like so:
./rebar compile eunit
you can try quote parameters instead of listing.
erl -noshell -pa ./ebin -s eunit test "test_module verbose" -init stop
More than eight years passed since the question, but there's still a nice solution not mentioned in the previous answers.
Once you are using EUnit, you can leverage from some of it's "automagic" features. One of them is an automatic export of the test/0 function, containing all the tests for the module.
So, if you are writing your tests alongside with the source code in the same module, all you have to do is:
$ erl -noshell -run your_module test -run init stop
If you are writing the tests in a separated, dependent module (as you should), you have to point to that module:
$ erl -noshell -run your_module_tests test -run init stop
All this will work fine, but the test won't be run in verbose mode as the OP required, but this is simple to solve with the EUNIT environment variable set to verbose.
Final version:
$ EUNIT=verbose erl -noshell -run your_module_tests test -run init stop
Have fun with Erlang and EUnit!
I use this script: https://github.com/lafka/dotconfig/blob/master/bin/eunit-module to run eunit on specific modules.
Example:
eunit-module <module> src ebin -I deps
That will do a couple of things:
Arg #2 is the directory where .erl resides
Arg #3 is the directory to output the compiled .beam
Arg #4++ is all the additional paths to add to your code path
Using -I specifies additional code paths AND where to look for files referenced with -include_lib
Erlang was already installed:
$dpkg -l|grep erlang
ii erlang 1:13.b.3-dfsg-2ubuntu2 Concurrent, real-time, distributed function
ii erlang-appmon 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP application monitor
ii erlang-asn1 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP modules for ASN.1 support
ii erlang-base 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP virtual machine and base applica
ii erlang-common-test 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP application for automated testin
ii erlang-debugger 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP application for debugging and te
ii erlang-dev 1:13.b.3-dfsg-2ubuntu2 Erlang/OTP development libraries and header
[... many more]
Erlang seems to work:
$ erl
Erlang R13B03 (erts-5.7.4) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.7.4 (abort with ^G)
1>
I downloaded lfe from github and checked out 0.5.2:
git clone http://github.com/rvirding/lfe.git
cd lfe
git checkout -b local0.5.2 e207eb2cad
$ configure
configure: command not found
$ make
mkdir -p ebin
erlc -I include -o ebin -W0 -Ddebug +debug_info src/*.erl
#erl -I -pa ebin -noshell -eval -noshell -run edoc file src/leex.erl -run init stop
#erl -I -pa ebin -noshell -eval -noshell -run edoc_run application "'Leex'" '"."' '[no_packages]'
#mv src/*.html doc/
Must be something stupid i missed :o
$ sudo make install
make: *** No rule to make target `install'. Stop.
$ erl -noshell -noinput -s lfe_boot start
{"init terminating in do_boot",{undef,[{lfe_boot,start,[]},{init,start_it,1},{init,start_em,1}]}}
Crash dump was written to: erl_crash.dump
init terminating in do_boot ()
Is there an example how I would create a hello world source file and compile and run it?
No, there is nothing you missed. The Makefile in LFE is "less than perfect" and should be ignored, it will be improved upon in the next release. To compensate all the needed files have already compiled and the .beam files are in the ebin directory. As it is not part of OTP I don't think it should ever install there.
The easiest way to handle this to create a private erlang library directory and point the environment variable ERL_LIBS to it. Then just drop the whole LFE directory there. When erlang starts the code server will automatically add the lfe/ebin directories into the path and the .beam files there will automagically be found and loaded. This will work with any package that contains an ebin directory. This also works on Windows. So:
Make an libs directory, say ~/erlang/lib
Set the environment variable ERL_LIBS, export ERL_LIBS=~/erlang/lib
Put the whole LFE directory there
When you start erlang you will then see /Users/rv/erlang/lib/lfe/ebin (or wherever you have it) in the code path (code:get_path()). You will then also be able to start the LFE shell directly with
erl -noshell -noinput -s lfe_boot start
There will be an lfe and an lfe.bat which does this included as well in the future.
As with erlang any text editor will work to edit LFE. For emacs there is an LFE mode which is still rather basic but works. You cannot yet run LFE in a window. Soon. The best way to include this is to put the following in your .emacs file:
;; LFE mode.
(setq load-path (cons "/Users/rv/erlang/lib/lfe/emacs" load-path))
(require 'lfe-start)
There are some example files in lfe/examples, all should work. In lfe/test/visual there is a bunch of my test files which have been included as example files. To compile an LFE file from the normal erlang shell do
lfe_comp:file("foo").
l(foo). %No autloload here, do this to ensure loading
while from the LFE shell do:
(c '"foo") ;This will autoload
There is a bunch of documentation in lfe/docs which is quite accurate but the user_guide.txt needs to be extended. There is also a Google group for LFE at
http://groups.google.se/group/lisp-flavoured-erlang
which contains some interesting discussions and people have written quite a lot in the github LFE wiki.
That's about it I think. contact me if/when you have more questions.
I have an Emakefile that looks like:
%% --
%%
%% --
{'/Users/user/projects/custom_test/trunk/*',
[debug_info,
{outdir, "/Users/user/projects/custom_test/trunk/ebin"},
{i, "/Users/user/projects/custom_test/trunk/include/."}
]
}.
What is an explanation in layman's terms for what each item does in the list?
How do I run the emakefile so that I am able to compile it?
After compilation, how do I run that generated BEAM file?
1/ {"source files globbed", Options}
Here the options are :
debug_info add debug info for the debugger
{outdir, "/Users/user/projects/custom_test/trunk/ebin"} where should the output be written (the .beam files)
{i, "/Users/user/projects/custom_test/trunk/include/."} where to find the .hrl header files.
2/ erl -make
3/ erl -pa /Users/user/projects/custom_test/trunk/ebin starts a shell.
Find the module serving as an entry point in your application and call the functions :
module:start().
You can also run the code non interactively :
erl -noinput -noshell -pa /Users/user/projects/custom_test/trunk/ebin -s module start
For the Emakefile synax visit the man page
In the directory where the Emakefile is run erl -make to compile using the Emakefile
Simplest way to run would be to simply start an erlang shell in the same directory as the beam files with the command erl. Then run the code with module_name:function_name(). (including the dot).