Puni

Parentheses Universalistic

• What is it?
  • A set of soft deletion commands
  • A factory of soft deletion commands
  • Sexp navigating & manipulating commands
  • Out of box support for many major modes
• Comparison with other packages
  • ParEdit & Lispy
  • Smartparens
• Quick start
• Commands
  • Deletion commands
  • Navigation commands
  • Marking commands
  • Sexp manipulating commands.
    • puni-squeeze
    • slurp & barf
    • puni-raise
    • puni-convolute
    • Other commands
• Define your own soft deletion commands
  • strict-sexp
  • style
  • fail-action
  • Conclusion
• Caveats
  • Doesn't work well in some major modes
  • Lack of auto pairing
• What does "Puni" means anyway?
• Contributing
• Donation

What is it?

A set of soft deletion commands

Puni contains commands for soft deletion, which means deleting while keeping parentheses (or other delimiters, like html tags) balanced. Let's see them in action:

Kill lines softly in Lisp code (emacs-lisp-mode):

In LaTeX document (tex-mode):

In HTML template (web-mode):

Look how it kills softly inside/between/out of tags.

In shell script (sh-mode):

Puni knows the ) is just a suffix of a condition, not a closing delimiter.

A factory of soft deletion commands

That's not the whole story. Puni offers a simple yet powerful API, puni-soft-delete-by-move, for you to define soft delete commands in a style that fits your need and taste.

For example, the default puni-backward-kill-word behaves like:

(foo bar)|
;; call `puni-backward-kill-word'
(foo |)

| means the cursor position. If you don't like this, you could define my-backward-kill-word that behaves like:

(foo bar)|
;; call `my-backward-kill-word'
(foo |bar)

The default puni-kill-line behaves like:

| foo (bar
       baz)
;; call `puni-kill-line'
|
;; (nothing left)

While you can define a my-kill-line that's not so greedy:

| foo (bar
       baz)
;; call `my-kill-line'
| (bar
       baz)
;; call `my-kill-line' again
|
;; (nothing left)

It's very easy to define commands like this. I'll show you how to do this later.

Sexp navigating & manipulating commands

As Puni understands the "balanced expression" concept, it offeres you commands to move by sexps, and manipulating sexps. Think about ParEdit, but works for Lisp and other languages.

Here's an example of slurping & barfing in HTML (in web-mode):

Notice the ending delimiter is blinked as a visual cue.

Out of box support for many major modes

That's still not the whole story. Let me reveal the ultimate truth of Puni, hang tight...

There are absolutely no language-specific logic inside Puni!

Wait, it can't be! Or how does it support web-mode and tex-mode?

Well, it turns out Emacs has a built-in function that knows what is a balanced expression (or, a sexp): forward-sexp. If we call forward-sexp until it throws an error, we know we've hit the boundary, so it's safe to delete until this position. Try this in some Lisp code:

(foo |bar)
;; call `forward-sexp'
(foo bar|)
;; call `forward-sexp'
(foo bar|) ;; (Signals an error)

A major mode can provide a forward-sexp-function. Ideally, it should work like the built-in forward-sexp, but unfortunately, many of these forward-sexp-functions have all sorts of problems, with the prominent one being jumping out of current sexp to search for a start/end of a sexp. For example, in web-mode:

<|p>foo</p>
<!-- call `forward-sexp` -->
<p>|foo</p>
<!-- what we really want -->
<p|>foo</p>

Puni fixes the behavior of these forward-sexp-functions in a generic way, by:

• Consecutively call forward-sexp, in different directions
• Syntax table
• Common sense

So we get puni-strict-forward-sexp and puni-strict-backward-sexp. These are "strict" versions of the forward-sexp fucntion available in current major mode, which means they move forward one sexp at a time, and stops at the boundary. This is the "ideal" forward-sexp function, and is the basis of all the commands offered by Puni.

By taking this appraoch, Puni supports many major modes out of the box.

And that really is the whole story ;)

Comparison with other packages

ParEdit & Lispy

ParEdit is a minor mode for structured editing of Lisp code. It implements soft deletion, and sexp manipulating commands, as Puni does.

Compared to ParEdit, Puni's pros:

• Supports many major modes, not only Lisp.
• An API for defining your own soft deletion commands.

Puni's cons:

• Puni doesn't implement down-list, so it lacks commands that needs to go into a list, like joining the sexps before and after point.
• Many of ParEdit's behavior is specially tweaked for Lisp, like inserting a ( will also insert a space before it when proper. Puni doesn't do that.

ParEdit could be mostly replaced by Puni. But if you are wondering if there are still more efficient way of editing Lisp code, maybe Lispy is for you.

Lispy is like ParEdit, with shorter (mostly single-key, without modifier) keybindings. It feels like modal editing for Lisp, that means the commands are faster to execute, and easier to combine to form complex operations. This keybinding design is the killer feature of Lispy.

Lispy also offers much more commands than ParEdit, focusing on faster move, inline help, code evaluation, semantic transformation of Lisp code, etc. These features are implemented for Python, Julia, and several Lisp dialects.

Smartparens

Smartparens is ParEdit for all languages, like Puni.

It takes a different approach than Puni: instead of making use of Emacs built-in mechanisms, it creates its own extensible machine for parsing pairs, and extends it for many languages. The result: It's around 10k lines of code, while Puni is around 2k lines.

At present, the main problem of smartparens is many bugs aren't fixed for years. For example, due to changes in the architecture, HTML related functionality has been slowly breaking down, and there has been no effort to save it. Now you'll encounter many problems using smartparens in web-mode. The biggest one, to me, is sp-kill-hybrid-sexp (the equivalent of puni-kill-line) is not working in web-mode.

Puni lacks some commands that smartparens has. But the advantages are:

• Puni has simpler architecture and much less code, so it's easier to maintain.
• Puni contains no language-specific logic, so there'll never be situations like "I don't want to fix a bug for you because I don't use that language".
• Again, an API for defining your own soft deletion commands.
• At present, Puni is in a healthier state. You've already seen it works well in web-mode ;)

Quick start

1. Clone this repository:

   $ git clone https://github.com/AmaiKinono/puni.git /path/to/puni/
   

2. Add the path to your load-path in your Emacs configuration:

   (add-to-list 'load-path "/path/to/puni/")

3. Require puni in your config:

   (require 'puni)

4. puni-mode offers keybindings for some pre-defined soft delete commands. You can enable puni-global-mode to enable them everywhere, and add puni-disable-puni-mode to mode hooks where you don't want to use Puni:

   (puni-global-mode)
   (add-hook 'term-mode-hook #'puni-disable-puni-mode)

   Or you can enable puni-mode only for programming and structured markup languages:

   (dolist (hook '(prog-mode-hook sgml-mode-hook nxml-mode-hook tex-mode-hook eval-expression-minibuffer-setup-hook))
     (add-hook hook #'puni-mode))

Here are 2 configuration examples using use-package:

;; Use puni-mode globally and disable it for term-mode.
(use-package puni
  :defer t
  :init
  ;; The autoloads of Puni are set up so you can enable `puni-mode` or
  ;; `puni-global-mode` before `puni` is actually loaded. Only after you press
  ;; any key that calls Puni commands, it's loaded.
  (puni-global-mode)
  (add-hook 'term-mode-hook #'puni-disable-puni-mode))

;; Use puni-mode only for certain major modes.
(use-package puni
  :defer t
  :hook ((prog-mode sgml-mode nxml-mode tex-mode eval-expression-minibuffer-setup) . puni-mode))

Commands

Deletion commands

First we have some "delete by move" commands:

Command	Default keybinding
puni-forward-delete-char	C-d
puni-backward-delete-char	DEL
puni-forward-kill-word	M-d
puni-backward-kill-word	M-DEL
puni-kill-line	C-k
puni-backward-kill-line	C-S-k

When there is an active region, puni-forward-delete-char and puni-backward-delete-char try to delete/kill that region instead (This behavior respects the variable delete-active-region). If it will cause an unbalanced state, Puni asks you to confirm.

You can also call puni-kill-active-region directly. It's bind to C-w.

puni-force-delete (C-c DEL) is for deleting the char before point, or the active region, no matter they are balanced or not. This is handy if you break the syntax structure by accident, and Puni doesn't allow you to delete something. I personally bind it to C-h as I use it often, and C-h is the shortcut in the terminal to kill a char backward.

Navigation commands

We have some "navigate by sexp" commands:

Command	Default keybinding
puni-forward-sexp	C-M-f
puni-backward-sexp	C-M-b
puni-beginning-of-sexp	C-M-a
puni-end-of-sexp	C-M-e

puni-forward/backward-sexp are similar to their built-in versions, but based on Puni's "strict forward/backward sexp" functions, so the behavior is more predictable, and won't take you out of current sexp.

When you call puni-beginning-of-sexp, it will take you to the point after the opening delimiter, then before it, then after another one... So consecutively calling it will take you all the way across opening delimiters. Same to puni-end-of-sexp.

While we can go out sexps using puni-beginning/end-of-sexp, it's hard to implement commands that goes into a sexp. As an alternative, Puni provides these commands:

Command	Default keybinding
puni-syntactic-forward-punct	M-(
puni-syntactic-backward-punct	M-)

These commands basically takes you to the next/previous punctuation, but it does more than that to give you a "syntactical navigating" feel. See their docstrings for detail. These are also handy in text-mode.

Marking commands

Puni offeres commands to mark things:

• puni-mark-sexp-at-point
• puni-mark-list-around-point
• puni-mark-sexp-around-point
• puni-expand-region

puni-expand-region is designed to be called consecutively. It marks the sexp at point, then the list around point, then the sexp around point, then the list containing the sexp around point... In short, it expands the active region by semantic units.

These commands don't have pre-defined keybindings in puni-mode.

Sexp manipulating commands.

These commands don't have pre-defined keybindings in puni-mode.

puni-squeeze

This copies the list around point (which is the part inside the sexp around point), and delete the sexp around point. It can be used to "rewrap" a sexp:

foo (bar|) baz
;; Call `puni-squeeze'
foo | baz
;; Type in a pair of brackets
foo [|] baz
;; Call `yank'
foo [bar|] baz

When there's an active balanced region, this copies the region and delete the sexp around it.

slurp & barf

There are 4 these commands:

• puni-slurp-forward
• puni-barf-forward
• puni-slurp-backward
• puni-barf-backward

They move the delimiters of the sexp around point across sexps around it. It's better to understand them using an example:

foo (bar|) baz
;; Call `puni-slurp-forward'
foo (bar| baz)
;; Call `puni-barf-forward'
foo (bar|) baz
;; Call `puni-slurp-backward'
(foo bar|) baz
;; Call `puni-barf-backward'
foo (bar|) baz

puni-raise

This uses the sexp at point to replace its parent sexp.

(or |(func1) (func2))
;; Call `puni-raise'
|(func1)

If there's an active balanced region, this replaces the region's parent sexp with it.

puni-convolute

This exchanges the order of application of two closest outer forms.

(let ((var (func)))
  (some-macro
    |body))
;; Call `puni-convolute'
(some-macro
  (let ((var (func)))
    |body))

Other commands

• puni-splice: Unwrap the sexp around point.
• puni-split: Split the sexp around point into two.
• puni-transpose: Swap the sexps before and after point.

Define your own soft deletion commands

The API for this is puni-soft-delete-by-move. Let's see a simplified definition of puni-kill-line. Notice the comments about arguments of puni-soft-delete-by-move:

(defun puni-kill-line ()
  "Kill a line forward while keeping expressions balanced."
  (interactive)
  (puni-soft-delete-by-move
   ;; FUNC: `puni-soft-delete-by-move` softly deletes the region from
   ;; cursor to the position after calling FUNC.
   (lambda ()
     (if (eolp) (forward-char) (end-of-line)))
   ;; STRICT-SEXP: More on this later.
   'strict-sexp
   ;; STYLE: More on this later.
   'beyond
   ;; KILL: Save deleted region to kill-ring if non-nil.
   'kill
   ;; FAIL-ACTION argument is not used here.
   ))

strict-sexp

If strict-sexp is nil, symbols are treated as sexps, even if they are actually delimiters. For example, in ruby-mode:

|def func
    puts "Hello"
end
# call `puni-kill-line`
|
# (nothing left)

Let's change strict-sexp to nil:

|def func
    puts "Hello"
end
# call `puni-kill-line`
|
    puts "Hello"
end

style

The default style of puni-kill-line is beyond. It means deleting sexps until no more to delete, or we've reached a position after the line end. For example:

| foo (bar
       baz)
;; call `puni-kill-line`
|
;; (nothing left)

The within style is basically the same, but it stops before the line end:

| foo (bar
       baz)
;; call `puni-kill-line`
|(bar
       baz)
;; call `puni-kill-line`
|(bar
       baz)
;; (nothing happened, as the line end is inside the next sexp)

We can combine within style with fail-action being delete-one, so when there's no complete sexp before the line end to delete, it deletes one sexp forward:

| foo (bar
       baz)
;; call `puni-kill-line`
|(bar
       baz)
;; call `puni-kill-line`
|
;; (nothing left)

The precise style means deleting until the line end, but only when the part between the cursor and line end is balanced:

|(foo bar)
;; call `puni-kill-line`
|
;; (nothing left)

;; another situation:
|(foo
  bar)
;; call `puni-kill-line`
|(foo
  bar)
;; (nothing happened)

This style is more useful for deletion in smaller regions, like word and char.

fail-action

This argument decides what to do if nothing can be deleted according to style. Let's take puni-backward-kill-word as an example, its style is precise. So in this example:

(foo bar)|

It can't delete anything.

If fail-action is nil, it does nothing.

If fail-action is delete-one, it deletes backward one sexp:

|
;; (nothing left)

If fail-action is jump, it jumps to the beginning of the previous word:

(foo |bar)

If fail-action is jump-and-reverse-delete (the one used by puni-backward-kill-word), it jumps to the the beginning of the previous word, and soft delete from here to the previous cursor position (the line end in this case), with style being within:

(foo |)

Conclusion

puni-soft-delete-by-move is a simple API for defining soft deletion commands. It has 2 key arguments: style decides which part to delete, and fail-action decides what to do if nothing can be deleted. By combining these 2 arguments, you can create soft deletion commands that fits your need and taste.

If this is not enough, read the "APIs" section in the source code. Puni further provides:

• Sexp navigating/locating functions: Move by sexps, locating the boundary of sexps/lists.
• puni-region-balance-p: Test if region is balanced.
• puni-soft-delete: Similar to puni-soft-delete-by-move but you need to tell it delete from which point to which point directly.
• Other tool functions.

Be sure to use the implementation of built-in commands as a reference when defining your own commands. Also, read the wiki for inspirations.

Caveats

Let's talk about things that Puni can't do, or doesn't do well.

Doesn't work well in some major modes

If the forward-sexp-function in a major mode has absolutely no idea about a syntax structure, then Puni can't deal with it. For example, in html-mode:

<p>hello|</p>
<!-- call `forward-sexp` -->
<p>hello</p>|
<!-- call `backward-sexp` -->
<p>hello|</p>

html-mode thinks </p> itself is a complete sexp, so Puni will just happily delete it:

<p>hello|</p>
<!-- call `puni-kill-line` -->
<p>hello

xml-mode and web-mode doesn't have this problem.

In general, it's still safe to enable puni-mode everywhere, as even if a major mode doesn't implement its own forward-sexp-function, the built-in one (that works well with Lisp) is used as a fallback, which works for brackets ((), [], {}) and strings. For many languages, this is enough. Besides, we can always use puni-force-delete to temporarily get rid of the restrictions set up by Puni.

It's worth noting that Emacs comes with a great indentation engine called SMIE. With it, a major mode can provide a table of grammar rules, and get:

• reliable auto-indentation
• a forward-sexp-function, which is what Puni needs.

There are many major modes using SMIE, like ruby-mode, sh-mode and css-mode. As SMIE is being used in a growing number of major modes, they get support from Puni, for free.

Lack of auto pairing

Puni doesn't support auto pairing, as I haven't found a way to implement it in a generic way. If you have any idea about this, please tell me!

For now, you can use these for auto pairing:

• electric-pair-mode: It's a built-in minor mode that automatically close your opening brackets. Its default behavior is carefully designed to keep brackets balanced when you insert things. I use this package daily, and I love it.

  It's disadvantage is that only single-character brackets (like (/), [/], ") are supported. You can't auto close delimiters like if ... end if or <p> ... </p>.

• Some major/minor modes come with their own tools for auto-pairing. For example, web-mode can auto close html tags, tex-mode has latex-close-block command.

• For major modes using SMIE, there's a smie-close-block command.

What does "Puni" means anyway?

"punipuni"（ぷにぷに）is a Japanese mimetic word means "soft", "bouncy", or "pillowy".

If you are surrounded by punipuni things, you feel safe and relieved. That's my feeling when using Puni: never need to worry about messing up parentheses anymore.

Contributing

PRs and issues are welcomed!

But please keep in mind that, due to the unique approach Puni takes, it can't fix every use case in every language, or we'll end up with a lot of ad-hoc tricks, which contradicts with the unified approach taken by Puni.

So, before you report a bug of the commands, I'd like you to:

• Make sure you've read README thoroughly, and have at least a vague concept of how Puni works.

• Try forward-sexp and backward-sexp around the thing you want to delete/manipulate on, and get an idea of how they understand the syntactic structure around there.

  Here we are talking about the built-in forward/backward-sexp commands, not puni-forward/backward-sexp. When puni-mode is enabled, C-M-f and C-M-b are bind to the latter ones.

• Now, if you think there's any hope that it can be solved, post an issue with the investigations you've made.

Donation

If Puni makes you happy, please consider buying me a beer to make me happy ;)

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• by Wechat Pay

  

• by Buy me a coffee