Configuration

Erlang Compiler Options

Configuration Key: erl_opts

Location: rebar.config or app-specific config

Common Options:

{erl_opts, [
    debug_info,                    % Include debug information
    warnings_as_errors,            % Treat warnings as errors
    {parse_transform, Module},     % Apply parse transform
    {d, 'MACRO'},                  % Define macro
    {d, 'MACRO', Value},           % Define macro with value
    {i, "include"},                % Include directory
    {platform_define, Regex, Def}, % Platform-specific defines
    {src_dirs, ["src", "lib"]},    % Additional source directories
    no_debug_info,                 % Exclude debug information
    inline_list_funcs             % Inline list functions
]}.

First Files

Configuration Key: erl_first_files

Purpose: Compile specific files before others

Example:

{erl_opts, [
    {erl_first_files, ["src/parser.erl", "src/types.erl"]}
]}.

Use Cases:

• Parse transforms (must compile before files using them)
• Type definitions (for other modules)
• Macros (defined in one file, used in others)

Extra Source Directories

Configuration Key: extra_src_dirs

Purpose: Additional source directories with separate compilation

Example:

{extra_src_dirs, [
    "test",
    {"scripts", [{recursive, true}]}
]}.

Behavior:

• Compiled to _build/PROFILE/extras/DIR/
• Not included in application's .app file modules list
• Use for tests, scripts, examples

Parallel Compilation

Configuration Key: jobs

Default: Number of logical CPU cores

Example:

{jobs, 4}.  % Use 4 parallel workers