erl_id_trans.3erl - Man Page

An identity parse transform.


This module performs an identity parse transformation of Erlang code. It is included as an example for users who wants to write their own parse transformers. If option {parse_transform,Module} is passed to the compiler, a user-written function parse_transform/2 is called by the compiler before the code is checked for errors.

Before the function parse_transform is called, the Erlang Compiler checks if the parse transformation can handle abstract code with column numbers: If the function parse_transform_info/0 is implemented and returns a map where the key error_location is associated with the value line, the compiler removes column numbers from the abstract code before calling the parse transform. Otherwise, the compiler passes the abstract code on without modification.


parse_transform(Forms, Options) -> Forms


Forms = [erl_parse:abstract_form() | erl_parse:form_info()]
Options = [compile:option()]

Performs an identity transformation on Erlang forms, as an example.

parse_transform_info() -> Info


Info = #{'error_location' => 'column' | 'line'}

Returns information about the parse transform itself.

Parse Transformations

Parse transformations are used if a programmer wants to use Erlang syntax, but with different semantics. The original Erlang code is then transformed into other Erlang code.


Programmers are strongly advised not to engage in parse transformations. No support is offered for problems encountered.

See Also

erl_parse(3), compile(3)

Referenced By


stdlib 3.15 Ericsson AB Erlang Module Definition