Erlang Pipeline Parse Transform

November 19, 2021 · View on GitHub

What is it?

Sometimes erlang programmer wants to apply function composition. Usually it is done by ugly combining functions, e.g.

Result = fun3(mod2:fun2(fun1(Arg1, Arg2))).

Other way to do that is creating multiple bindings:

R1 = fun1(Arg1, Arg2),
R2 = mod2:fun2(R1),
Result = fun3(R2).

This parse transform allows the user to write like this:

Result = [fun1, mod2:fun2, fun3] (Arg1, Arg2).

More complicated options are available -- see src/pipeline_demo.erl for examples.

Add the following in your dependencies

{deps, [
    ...
    {pipeline, {pkg, erl_pipeline}}   %% <--- That's line to add
]}.

You want to make sure you specify it that way, with the application being called pipeline and the package being called erl_pipeline.

If you're still on rebar2 (trust me, I get it, no judgment here, I totally get it), add this to your deps:

{deps, [
    {pipeline, {git, "https://github.com/choptastic/pipeline", {branch, master}}}
]}.

To use pipeline, simply compile your modules with -compile({parse_transform, pipeline}). module attribute.