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Emacs Lisp layer

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emacs.png

1 Description

This layer gathers all the configuration related to emacs-lisp. This should always be in your dotfile, it is not recommended to uninstall it.

1.1 Features:

  • Auto-completion using company
  • Linting using flycheck integration
  • Linting package file metadata using flycheck-package
  • Repl support via IELM
  • Support for specific lisp navigation styles via emacs-lisp-mode
  • Auto-compile via auto-compile package
  • Debugging via edebug
  • Ert test runner with overseer
  • Nameless package prefix with optional nameless
  • Structurally safe editing using optional evil-cleverparens
  • Visual feedback when evaluation using eval-sexp-fu

2 Install

To use this configuration layer, add it to your ~/.spacemacs. You will need to add emacs-lisp to the existing dotspacemacs-configuration-layers list in this file.

3 Auto-compile

This layer adds the auto-compile package to automatically keep the byte-compiled version of your Emacs lisp files synced with the uncompiled version on every save. If there are any compiler errors in the file, you will see a counter show up in the mode line. You can hover over these numbers to get a description or view the compiler output with the SPC m c l key binding. To disable the feature use this line in your dotspacemacs/user-config function.

(remove-hook 'emacs-lisp-mode-hook 'auto-compile-mode)

You can also exclude the auto-compile package.

4 Working with lisp files (barfage, slurpage & more)

Spacemacs comes with a special lisp-state for working with lisp code that supports slurpage, barfage and more tools you'll likely want when working with lisp.

As this state works the same for all files, the documentation is in global DOCUMENTATION.org. In general, use SPC k to interact with the lisp-state.

5 Debugging Elisp

Here is an interactive quick start to debug Emacs Lisp.

First you need to read this file in Emacs in order to have the following code block to be interactively opened as Emacs Lisp.

(defun helloworld (name)
  (let ((n (subroutine name)))
    (message (format "Hello world, %s!" name))))

(defun subroutine (s)
  (concat "my dear " s))

(helloworld "Spacemacs")

Steps:

  1. To start the tutorial put your point in the source block above and press , '

it will open a new buffer in emacs-lisp-mode.

  1. Evaluate each sexp by putting your point in each of them and press , e f.
  2. To debug the helloworld function, put your cursor on the defun keyword and

press SPC m d f (or , d f), it will put a breakpoint on the function (we say that we instrumentalise this function) so whenever the Lisp interpreter encounters this function it will start the debugger.

  1. Then go to the closing parenthesis of (helloworld "Spacemacs") and press

, e e to evaluate it, if you are using vim editing style you end up in evilified state otherwise you end up in emacs state and *Debugging* is displayed in the mode line.

  1. Press s to go to next step up to the opening parenthesis of (subroutine name),
  2. Press i to go into the subroutine where you can press s to step in

function or press o to go out of it.

  1. Press a to stop debugging.

6 Nameless

Nameless hides package namespaces in your emacs-lisp code, and replaces it by leading > It can be toggled with SPC m T n.

By default nameless is deactivated, to enable it set the layer variable emacs-lisp-hide-namespace-prefix to t.

NOTE: nameless is known to cause problems when spacemacs is used inside a terminal window, use with caution.

(setq-default dotspacemacs-configuration-layers '(
  (emacs-lisp :variables emacs-lisp-hide-namespace-prefix t)))

6.1 Aliases

This layer defines some global aliases for Spacemacs:

alias namespace
.S dotspacemacs
CL configuration-layer
S spacemacs
SB spacemacs-buffer

You can define additional alias in function dotspacemacs/user-config of your dotfile:

(add-to-list 'nameless-global-aliases '("N" . "nameless"))

7 Structurally safe editing

This layer adds support for evil-cleverparens which allows to safely edit lisp code by keeping the s-expressions balanced.

By default this mode is not activated. You can turn it on locally on the active buffer with SPC m T s (s for safe).

To turn it on automatically for all emacs-lisp buffers call the following function in your dotspacemacs/user-config function:

(spacemacs/toggle-evil-safe-lisp-structural-editing-on-register-hook-emacs-lisp-mode)

or to enable it for all supported modes:

(spacemacs/toggle-evil-safe-lisp-structural-editing-on-register-hooks)

When enabled the symbol πŸ†‚ should be displayed in the mode-line.

8 Key bindings

Key binding Description
SPC m g g go to definition of symbol under point
SPC m g G go to definition of symbol under point in other window
SPC m h h describe symbol at point
SPC m c c byte compile the current file
SPC m c l popup compile-log buffer
SPC m e $ or SPC m e l go to end of current line and evaluate
SPC m e b evaluate current buffer
SPC m e C evaluate current defun or setq
SPC m e e evaluate sexp before point
SPC m e f evaluation current function
SPC m e r evaluate current region
~SPC m ​,​~ toggle lisp state
SPC m t b run tests of current buffer
SPC m t q run ert
SPC m d m open macrostep transient-state
SPC m : toggle nameless minor mode

8.1 Additional testing functions with overseer

Function related to test are present under the SPC m t prefix:

Key binding Description
SPC m t a overseer test
SPC m t A test debug
SPC m t t run test
SPC m t b test buffer
SPC m t f test file
SPC m t g test tags
SPC m t p test prompt
SPC m t q test quiet
SPC m t h test help

8.2 Additional evaluation functions

If smartparens is used the following additional key bindings are available:

Key binding Description
SPC m e c evaluate sexp around point
SPC m e s evaluate symbol around point

8.3 Format code

The semantic layer should be installed for these key bindings to become active.

Key binding Description
SPC m = b format current buffer
SPC m = d format current function
SPC m = o format all on one line
SPC m = s format current sexp

8.4 Debugging

To start debugging:

Key binding Description
SPC m d f on a defun symbol toggle on the instrumentalisation of the function
SPC m d F on a defun symbol toggle off the instrumentalisation of the function
SPC m d t insert (debug) to print the stack trace and re-evaluate the function

In edebug-mode (*Debugging* is displayed in the minor modes segment of the mode line)

TODO

In debugger-mode (Debugger is displayed in major mode segment of the mode line)

TODO

Author: root

Created: 2019-11-10 Sun 14:17

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