:ui ligatures

ligatures and symbols to make your code pretty again

1. Description

This module enables ligatures and arbitrary symbol substitutions with mac-auto-operator-composition-mode (on supported macOS systems) or composition tables (harfbuzz on Emacs 28), falling back on prettify-symbols-mode otherwise.

1.1. Maintainers

This module has no dedicated maintainers. Become a maintainer?

1.2. Module flags

+extra
Enable extra symbol substitutions in certain modes, for example lambda in lisps are replaced with λ.

1.2.1. Font ligatures module flags

This module provides four flags for enabling fall-back ligature support for a particular font. They are:

+fira
Enables Fira Code ligatures. This requires Fira Code Symbol and a patched version of Fira Code (see below).
+hasklig
Enable Hasklig ligatures. This requires a patched version of the HaskLig font (see below).
+iosevka
Enable Iosevka ligatures. This requires a patched version of the Iosevka font (see below).
+pragmata-pro
Enable Pragmata Pro ligatures. This requires the Pragmata Pro font.

All these flags are ignored if you’re sporting either a) Emacs 28+ with Harfbuzz support (which can compose ligatures natively), or b) Mitsuharu’s emacs-mac build on macOS (which uses mac-auto-operator-composition-mode).

1.3. Packages

This module doesn’t install any packages.

1.4. Hacks

No hacks documented for this module.

2. Prerequisites

This module requires one of three setups for ligatures to work:

  • A recent enough version of Emacs which will compose ligatures automatically (Emacs 28 with Harfbuzz support), or
  • Mitsuharu’s emacs-mac build on macOS (available on homebrew), or
  • A patched font for Doom’s fallback ligature support.

2.1. Mitsuharu’s emacs-mac port or Emacs 28+ with Harfbuzz support

Ligatures should be handled without any additional configuration.

2.2. Not Emacs-mac and Emacs <= 27

  1. Enable one of the four ligature font flags: +fira, +hasklig, +iosevka or +pragmata-pro.
  2. Install the patched version of the associated font with M-x +ligatures/install-patched-font. Note: Pragmata Pro cannot be installed this way because it is a non-free font and must be purchased and installed manually.

3. TODO Usage

3.1. TODO Mathematical symbols replacement

3.2. Coding ligatures

This module includes configuration to compose combinations like -> or :: into prettier glyphs (called a ligature). Depending on the current version of emacs, this is implemented in two different ways :

prettify-symbols-mode method
this is the “legacy” method. It uses a font which haves the ligatures as separate unicode symbols, and using prettify-symbols-mode, ->-like combinations are manually listed and replaced with the correct symbol. The mapping between ->-like sequences and unicode values in the font are font-specific ; therefore +fira, +iosevka… files and specific fonts are necessary for it to work.
composition-function-table method
regexps are used to match all the usual sequences which are composed into ligatures. These regexps are passed to emacs directly, which asks Harfbuzz to shape it. Ligatures are obtained automatically depending on the capabilities of the font, and no font-specific configuration is necessary.

Emacs-mac port implements the composition-function-table method in its code, nothing is necessary on Doom side; otherwise, Doom implements the composition-function-table for emacs 28+ built with Harfbuzz support, and the prettify-symbols-mode method otherwise.

Even though harfbuzz has been included in emacs 27, there is currently a bug (#40864) which prevents a safe usage of composition-function-table method in emacs 27.

4. Configuration

4.1. Setting ligatures

If you want to set ligatures for modules that don’t have them by default you can use the set-ligatures! macro in your config el file

# ⎘
(after! PACKAGE
  (set-ligatures! 'MAJOR-MODE
    :symbol "keyword"))

eg.

# ⎘
(after! go-mode ; in this case the major mode and package named the same thing
  (set-ligatures! 'go-mode
    :def "func" ; function keyword
    :true "true" :false "false"
    ; this will replace not only definitions
    ; but coresponding functions aswell
    :int "int" :str "string"
    :float "float" :bool "bool"
    :for "for"
    :return "return" :yeild "yeild"))

you can set these symbols out of the box

# ⎘
(set-ligatures! 'MAJOR-MODE
    ;; Functional
    :lambda        "lambda keyword"
    :def           "function keyword"
    :composition   "composition"
    :map           "map/dictionary keyword"
    ;; Types
    :null          "null type"
    :true          "true keyword"
    :false         "false keyword"
    :int           "int keyword"
    :float         "float keyword"
    :str           "string keyword"
    :bool          "boolean keywork"
    :list          "list keyword"
    ;; Flow
    :not           "not operator"
    :in            "in operator"
    :not-in        "not in operator"
    :and           "and keyword"
    :or            "or keyword"
    :for           "for keyword"
    :some          "some keyword"
    :return        "return"
    :yield         "yeild"
    ;; Other
    :union         "Union keyword"
    :intersect     "Intersect keyword"
    :diff          "diff keyword"
    :tuple         "Tuple Keyword "
    :pipe          "Pipe Keyword" ;; FIXME: find a non-private char
    :dot           "Dot operator")

If you have multiple versions of the same keyword you can set the symbol twice

# ⎘
(set-ligatures! scala-mode
  :null "none"
  :null "None")

4.2. Changing ligatures

if you don’t like the symbols chosen you can change them by using…

# ⎘
;; you don't need to include all of them you can pick and mix
(plist-put! +ligatures-extra-symbols
  ;; org
  :name          "»"
  :src_block     "»"
  :src_block_end "«"
  :quote         "“"
  :quote_end     "”"
  ;; Functional
  :lambda        "λ"
  :def           "ƒ"
  :composition   "∘"
  :map           "↦"
  ;; Types
  :null          "∅"
  :true          "𝕋"
  :false         "𝔽"
  :int           "ℤ"
  :float         "ℝ"
  :str           "𝕊"
  :bool          "𝔹"
  :list          "𝕃"
  ;; Flow
  :not           "￢"
  :in            "∈"
  :not-in        "∉"
  :and           "∧"
  :or            "∨"
  :for           "∀"
  :some          "∃"
  :return        "⟼"
  :yield         "⟻"
  ;; Other
  :union         "⋃"
  :intersect     "∩"
  :diff          "∖"
  :tuple         "⨂"
  :pipe          "" ;; FIXME: find a non-private char
  :dot           "•")  ;; you could also add your own if you want

5. Troubleshooting

There are no known problems with this module. Report one?

6. TODO Appendix

This module has no appendix yet. Write one?