epipe
=====
[](https://travis-ci.org/oltarasenko/epipe)
Erlang pipes
Influenced by Elixir pipe (|>) and with operators. Brings similar functionality to erlang
Intro
-----
Probably you've seen code like this:
``` erlang
case gen_tcp:connect(Host, Port, Otps) of
{ok, Socket} ->
case do_handshake(Socket) of
ok -> send_message(Socket);
{error, Reason} -> exit(normal)
end;
{error, Reason} -> exit(normal)
end
```
Sometimes the amount of the nested cases goes even deeper.... Which makes the code quite
complex for understanding and debugging.
Epipe allows to rewrite it in a very flat way:
``` erlang
connect({Host, Port, Opts}) ->
case gen_tcp:connect(Host, Port, Otps) of
{ok, Socket} -> {ok, Socket};
{error, Reason} -> {error, Reason}
end.
handshake(Socket) ->
case do_handshake(Socket) of
ok -> {ok, Socket};
{error, Reason} -> {error, Reason}
end.
send_message(Socket) ->
case do_send_message(Socket) of
response -> {ok, response};
Error -> {error, Error}
end.
FunctionsList = [
{connect_fun, fun connect/1},
{handshake_fun, fun handshake/1},
{send_message_fun, fun send_message/1}
],
epipe:run(FunctionsList, {Host, Port, Opts}).
```
Which allows to 'pipe' the initial data through FunctionsList, stopping on any step
which would produce {error, ...} value.
Examples
--------------
```
sample1() ->
Fun1 = fun(Val) -> {ok, Val + 1} end,
Fun2 = fun(Val) -> {ok, Val + 2} end,
epipe:run([{add_one, Fun1}, {add_two, Fun2}], 0).
```
Would produce {ok, 3}
```
sample2() ->
Fun1 = fun(Val) -> {ok, Val + 1} end,
Fun2 = fun(Val) -> {error, "Can't process data"} end,
epipe:run([{step1, Fun1}, {step2, Fun2}, {step3, Fun1}], 0).
```
Would produce {error, step2, "Can't process data", 1}, giving not only error reason,
but also would give a hint, about the failing step.
Build
-----
$ rebar3 compile
