YASnippets for faster clojure coding
Yasnippets minimise typing for commonly used Clojure forms and documentation structures, or any other text regularly created. Yasnippets have placeholders that allow jumping (tabbing) to points in the snippet, so specific text can be added to the more generic text of the snippet.
Emacs YASnippet package uses mode-specific snippets that expand to anything from a simple text replacement to an intricate code block structure using placeholders to add specific values to the general form.
See YASnippet in action in this Emacs Yasnippet video.
Add custom snippets for Clojure or any other language you use with Spacemacs / Emacs
Additional ways to speed up typing Clojure code include creating projects from templates or general abbreviations with Emacs Abbrev modeSnippets are also part of Clojure LSP and can be used with any supporting editor.
Using snippets
Start typing the snippet name and press M-/ to yas-expand which replaces the name with the full text of the snippet.
Type defn and press M-/ to expand to the code of a function definition form. Use TAB to move through the placeholders to complete the name, doc-string, arguments and body of the function.
Smartparens is disabled when tabbing through a snippet
List snippets for current major mode
SPC i s (helm-yas) displays a completion buffer that lists the matching snippets available for the current major mode.
C-j and C-k to navigate the list and RET to insert and expand the snippet.
Add snippets to completion menu
The auto-completion layer shows a completion popup menu, with matching functions and other names from the REPL or Clojure LSP (clj-kondo). Configure the auto-completion layer to show YASnippets when typing.
Add the auto-completion-enable-snippets-in-popup variable to show snippets in the auto-completion popup.
Add auto-completion-enable-sort-by-usage to show the most commonly used snippets first in the list.
(auto-completion :variables
auto-completion-enable-snippets-in-popup t
auto-completion-enable-sort-by-usage t)
Matching snippets will now appear in the completion menu whilst typing
Default snippets for Clojure
The snippets available in Spacemacs can be found in the yasnippet github repository.
defn, require, let, ifl and for are often used by Practicalli.
NOTE: The
testsnippet generates adeftestform which by convention uses a name post-fixed with-test. PressingTABaftertestwill expand that word into another deftest form within the current deftest form.Press space after the
-testname to preventtestbeing expanded to adeftestform.
The current snippets for Clojure mode are in the following table, indicating which tab stops they have. mpenet/clojure-snippets includes several additional Clojure snippets (although are not part of yasnippets by default).
| Snippet | Description | Tab Stops |
|---|---|---|
| bench | benchmark an expression, using the time function | body |
| def | def expression | N/A |
| defm | defmacro expression, with name, doc-string, arguments & body tabstops | name, docstring, args, body |
| defn | defn expression, with name, doc-string, arguments & body tabstops | name, docstring, args, body |
| fn | fn - anonymous function | name, body |
| for | for | condition, body |
| if | if | condition, body |
| ifl | if-let - if true, bind a local name | binding, body |
| import | import java library | library name |
| is | is - clojure test assertion | value, expected |
| let | let - bind a local name to a value | name, value, body |
| map | map | fn, col, col |
| map.lambda | map with anonymous function #() | fn, body |
| mdoc | metadata docstring | docstring |
| ns | ns - expression with the current namespace inserted automatically | N/A |
| opts | destructure map with :keys, :or for default values, :as for arg vector | :key binding, or defaults, :as binding |
| pr | prn - print function | string/value |
println - print function | string/value | |
| reduce | reduce - reduce expression with an anonymous function | args, body |
| require | :require expression with library and alias | library, alias |
| test | deftest expression (not including testing part of a deftest expression) | test description, value/expected |
| try | try & catch expression | try expression, exception name, body |
| use | depreciated: use require instead | |
| when | when | when expression, body |
| whenl | when-let - local binding on when condition | binding, body |
Summary
Have fun speeding up the writing of your Clojure code (and any other common text structures) in Spacemacs / Emacs.
Consider writing custom snippets to extend those available via Yasnippets.
Article originally published on jr0cket.co.uk and has been migrated to practical.li/blog with some minor updates.
Thank you