erlang.el(3erl) Erlang Module Definition erlang.el(3erl)
NAME
erlang.el - Erlang mode for Emacs
DESCRIPTION
Possibly the most important feature of an editor designed for program-
mers is the ability to indent a line of code in accordance with the
structure of the programming language. The Erlang mode does, of course,
provide this feature. The layout used is based on the common use of the
language. The mode also provides things as syntax highlighting, elec-
tric commands, module name verification, comment support including
paragraph filling, skeletons, tags support etc.
In the following descriptions the use of the word Point means: "Point
can be seen as the position of the cursor. More precisely, the point is
the position between two characters while the cursor is drawn over the
character following the point".
INDENT
The following command are directly available for indentation.
* TAB (erlang-indent-command) - Indents the current line of code.
* M-C-\ (indent-region) - Indents all lines in the region.
* M-l (indent-for-comment) - Insert a comment character to the right
of the code on the line (if any).
Lines containing comment are indented differently depending on the num-
ber of %-characters used:
* Lines with one %-character is indented to the right of the code.
The column is specified by the variable comment-column, by default
column 48 is used.
* Lines with two %-characters will be indented to the same depth as
code would have been in the same situation.
* Lines with three of more %-characters are indented to the left mar-
gin.
* C-c C-q (erlang-indent-function) - Indents the current Erlang func-
tion.
* M-x erlang-indent-clause RET
-Indent the current Erlang clause.
* M-x erlang-indent-current-buffer RET - Indent the entire buffer.
EDIT - FILL COMMENT
When editing normal text in text mode you can let Emacs reformat the
text by the fill-paragraph command. This command will not work for com-
ments since it will treat the comment characters as words.
The Erlang editing mode provides a command that knows about the Erlang
comment structure and can be used to fill text paragraphs in comments.
Ex:
%% This is just a very simple test to show
%% how the Erlang fill
%% paragraph command works.
Clearly, the text is badly formatted. Instead of formatting this para-
graph line by line, let's try erlang-fill-paragraph by pressing M-q.
The result is:
%% This is just a very simple test to show how the Erlang fill
%% paragraph command works.
EDIT - COMMENT/UNCOMMENT REGION
C-c C-c will put comment characters at the beginning of all lines in a
marked region. If you want to have two comment characters instead of
one you can do C-u 2 C-c C-c
C-c C-u will undo a comment-region command.
EDIT - MOVING THE MARKER
* C-a M-a (erlang-beginning-of-function) - Move the point to the be-
ginning of the current or preceding Erlang function. With an nu-
meric argument (ex C-u 2 C-a M-a) the function skips backwards over
this many Erlang functions. Should the argument be negative the
point is moved to the beginning of a function below the current
function.
* M-C-a (erlang-beginning-of-clause) - As above but move point to
the beginning of the current or preceding Erlang clause.
* C-a M-e (erlang-end-of-function) - Move to the end of the current
or following Erlang function. With an numeric argument (ex C-u 2 C-
a M-e) the function skips backwards over this many Erlang func-
tions. Should the argument be negative the point is moved to the
end of a function below the current function.
* M-C-e (erlang-end-of-clause) - As above but move point to the end
of the current or following Erlang clause.
EDIT - MARKING
* C-c M-h (erlang-mark-function) - Put the region around the current
Erlang function. The point is placed in the beginning and the mark
at the end of the function.
* M-C-h (erlang-mark-clause) Put the region around the current Er-
lang clause. The point is placed in the beginning and the mark at
the end of the function.
EDIT - FUNCTION HEADER COMMANDS
* C-c C-j (erlang-generate-new-clause) - Create a new clause in the
current Erlang function. The point is placed between the parenthe-
ses of the argument list.
* C-c C-y (erlang-clone-arguments) - Copy the function arguments of
the preceding Erlang clause. This command is useful when defining a
new clause with almost the same argument as the preceding.
EDIT - ARROWS
* C-c C-a (erlang-align-arrows) - aligns arrows after clauses inside
a region.
Example:
sum(L) -> sum(L, 0).
sum([H|T], Sum) -> sum(T, Sum + H);
sum([], Sum) -> Sum.
becomes:
sum(L) -> sum(L, 0).
sum([H|T], Sum) -> sum(T, Sum + H);
sum([], Sum) -> Sum.
SYNTAX HIGHLIGHTING
The syntax highlighting can be activated from the Erlang menu. There
are four different alternatives:
* Off: Normal black and white display.
* Level 1: Function headers, reserved words, comments, strings,
quoted atoms, and character constants will be colored.
* Level 2: The above, attributes, Erlang bif:s, guards, and words in
comments enclosed in single quotes will be colored.
* Level 3: The above, variables, records, and macros will be colored.
(This level is also known as the Christmas tree level.)
TAGS
For the tag commands to work it requires that you have generated a tag
file. See Erlang mode users guide
* M-. (find-tag) - Find a function definition. The default value is
the function name under the point.
* Find Tag (erlang-find-tag) - Like the Elisp-function `find-tag'.
Capable of retrieving Erlang modules. Tags can be given on the
forms `tag', `module:', `module:tag'.
* M-+ (erlang-find-next-tag) - Find the next occurrence of tag.
* M-TAB (erlang-complete-tag) - Perform completion on the tag entered
in a tag search. Completes to the set of names listed in the cur-
rent tags table.
* Tags aprops (tags-apropos) - Display list of all tags in tags table
REGEXP matches.
* C-x t s (tags-search) - Search through all files listed in tags ta-
ble for match for REGEXP. Stops when a match is found.
SKELETONS
A skeleton is a piece of pre-written code that can be inserted into the
buffer. Erlang mode comes with a set of predefined skeletons. The
skeletons can be accessed either from the Erlang menu of from commands
named tempo-template-erlang-*, as the skeletons is defined using the
standard Emacs package "tempo". Here follows a brief description of the
available skeletons:
* Simple skeletons: If, Case, Receive, Receive After, Receive Loop -
Basic code constructs.
* Header elements: Module, Author - These commands insert lines on
the form -module(xxx). and -author('my@home').. They can be used
directly, but are also used as part of the full headers described
below.
* Full Headers: Small (minimum requirement), Medium (with fields for
basic information about the module), and Large Header (medium
header with some extra layout structure).
* Small Server - skeleton for a simple server not using OTP.
* Application - skeletons for the OTP application behavior
* Supervisor - skeleton for the OTP supervisor behavior
* Supervisor Bridge - skeleton for the OTP supervisor bridge behavior
* gen_server - skeleton for the OTP gen_server behavior
* gen_event - skeleton for the OTP gen_event behavior
* gen_fsm - skeleton for the OTP gen_fsm behavior
*
gen_statem (StateName/3) - skeleton for the OTP gen_statem behav-
ior using state name functions
*
gen_statem (handle_event/4) - skeleton for the OTP gen_statem be-
havior using one state function
* Library module - skeleton for a module that does not implement a
process.
* Corba callback - skeleton for a Corba callback module.
* Erlang test suite - skeleton for a callback module for the erlang
test server.
SHELL
* New shell (erlang-shell) - Starts a new Erlang shell.
* C-c C-z, (erlang-shell-display ) - Displays an Erlang shell, or
starts a new one if there is no shell started.
COMPILE
* C-c C-k, (erlang-compile) - Compiles the Erlang module in the cur-
rent buffer. You can also use C-u C-c C-k to debug compile the mod-
ule with the debug options debug_info and export_all.
* C-c C-l, (erlang-compile-display) - Display compilation output.
* C-u C-x` Start parsing the compiler output from the beginning. This
command will place the point on the line where the first error was
found.
* C-x` (erlang-next-error) - Move the point on to the next error. The
buffer displaying the compilation errors will be updated so that
the current error will be visible.
MAN
On unix you can view the manual pages in emacs. In order to find the
manual pages, the variable `erlang-root-dir' should be bound to the
name of the directory containing the Erlang installation. The name
should not include the final slash. Practically, you should add a line
on the following form to your ~/.emacs,
(setq erlang-root-dir "/the/erlang/root/dir/goes/here")
STARTING IMENU
* M-x imenu-add-to-menubar RET - This command will create the IMenu
menu containing all the functions in the current buffer.The command
will ask you for a suitable name for the menu. Not supported by
Xemacs.
VERSION
* M-x erlang-version RET - This command displays the version number
of the Erlang editing mode. Remember to always supply the version
number when asking questions about the Erlang mode.
Ericsson AB tools 3.4 erlang.el(3erl)