hamacs/ha-programming-clojure.org

#+TITLE:  Clojure Programming
#+AUTHOR: Howard X. Abrams
#+DATE:   2022-04-05
#+FILETAGS: :emacs:

A literate programming file for programming in Clojure.

#+begin_src emacs-lisp :exports none
  ;;; ha-programming-clojure --- programming in Clojure. -*- lexical-binding: t; -*-
  ;;
  ;; © 2022 Howard X. Abrams
  ;;   Licensed under a Creative Commons Attribution 4.0 International License.
  ;;   See http://creativecommons.org/licenses/by/4.0/
  ;;
  ;; Author: Howard X. Abrams <http://gitlab.com/howardabrams>
  ;; Maintainer: Howard X. Abrams
  ;; Created: April  5, 2022
  ;;
  ;; This file is not part of GNU Emacs.
  ;;
  ;; *NB:* Do not edit this file. Instead, edit the original literate file at:
  ;;            ~/other/hamacs/ha-programming-clojure.org
  ;;       And tangle the file to recreate this one.
  ;;
  ;;; Code:
  #+end_src
I like [[http://clojure.org][Clojure]] as a /modern Lisp/, but I don’t get to play with it much.
The following instructions create a fully blinged-out Emacs-Clojure setup.
* Introduction
To get Clojure working on a new system, try the following on a Mac:
#+begin_src sh
  brew install clojure/tools/clojure
#+end_src

And make sure it works:
#+begin_src sh
  clojure --help
#+end_src

Or by starting a REPL:
#+begin_src sh
  clj
#+end_src

Also, download this script:
#+begin_src sh
  curl -o ~/bin/lein https://raw.githubusercontent.com/technomancy/leiningen/stable/bin/lein
  chmod u+x ~/bin/lein
#+end_src

Then for each project, create the project directory with this command:
#+begin_src sh
  lein new app fresh-app
#+end_src
* Emacs Support
We begin with using [[https://github.com/clojure-emacs/clojure-mode/][clojure-mode]]:
#+begin_src emacs-lisp
  (use-package clojure-mode
    :init
    (add-to-list 'org-babel-load-languages '(clojure . t))

    :config
    (defun ha-prettify-clojure ()
      "Make the Clojure syntax prettier."
      (push '("fn"   . ?𝝀) prettify-symbols-alist)
      (push '("__"   . ?⁈) prettify-symbols-alist)
      (prettify-symbols-mode))

    :hook (clojure-mode . ha-prettify-clojure))
#+end_src

Need the IDE feature of [[https://github.com/clojure-emacs/cider][Cider]]:
#+begin_src emacs-lisp
  (use-package cider
    :commands (cider cider-connect cider-jack-in)
    :init
    (setq cider-auto-select-error-buffer nil
          cider-repl-pop-to-buffer-on-connect nil
          cider-repl-use-clojure-font-lock t
          cider-repl-wrap-history t
          cider-repl-history-size 1000
          cider-show-error-buffer t
          nrepl-hide-special-buffers t
          ;; Stop error buffer from popping up while working in buffers other than the REPL:
          nrepl-popup-stacktraces nil))
#+end_src
Read the entire [[https://docs.cider.mx/][CIDER manual]].
** Linting
Using [[https://github.com/jonase/eastwood#emacs--cider][Eastwood]] with the [[https://github.com/clojure-emacs/squiggly-clojure][Squiggly Clojure]] project to add lint warnings to [[file:emacs.org::*Flycheck][Flycheck]]:
  #+begin_src elisp
  (use-package flycheck-clojure
    :after flycheck
    :config
    (flycheck-clojure-setup))
  #+end_src
** Snippets

For clojure-specific templates for [[https://github.com/capitaomorte/yasnippet][yasnippets]], clone David Nolen's [[http://github.com/swannodette/clojure-snippets][clojure-snippets]] repository into my =snippets= directory:
  #+begin_src sh :tangle no
    git clone http://github.com/swannodette/clojure-snippets ~/.emacs/snippets/clojure-mode
  #+end_src

Or install it as a package:
  #+begin_src elisp
  (use-package clojure-snippets)
  #+end_src
** Refactoring
The [[https://github.com/clojure-emacs/clj-refactor.el][clj-refactor]] project:
  #+begin_src elisp
  (use-package clj-refactor
    :hook
    (clojure-mode . clj-refactor-mode)
    :config
    ;; Configure the Clojure Refactoring prefix:
    (cljr-add-keybindings-with-prefix "C-c .")
    :diminish clj-refactor-mode)
  #+end_src

The advanced refactorings require the [[https://github.com/clojure-emacs/refactor-nrepl][refactor-nrepl middleware]], which should explain why we added the =refactor-nrepl= to the =:plugins= section in the =~/.lein/profiles.clj= file (see below).

The /real problem/ is trying to remember all the [[https://github.com/clojure-emacs/clj-refactor.el/wiki][refactoring options]]. Remember: =C-c . h h=
** Org Babel
And of course, we want to put this with org blocks:
#+begin_src emacs-lisp
  (use-package ob-clojure
    :straight (:type built-in)
    :custom
    (org-babel-clojure-backend 'cider)
    :config
    (add-to-list 'org-babel-load-languages '(clojure . t)))
#+end_src

Does this now work?
#+begin_src clojure :results raw replace
  (format "The answer is %d" (+ (* 4 10) 2))
#+end_src

#+RESULTS:
"The answer is 42"
* LSP, a WIP
Check out the goodies in [[https://emacs-lsp.github.io/lsp-mode/tutorials/clojure-guide/][this essay]] for hooking Clojure to LSP. Haven’t done this yet.
#+begin_src emacs-lisp :tangle no
  (add-hook 'clojure-mode-hook 'lsp)
  (add-hook 'clojurescript-mode-hook 'lsp)
  (add-hook 'clojurec-mode-hook 'lsp)
#+end_src
* Technical Artifacts                                :noexport:
Let's =provide= a name so we can =require= this file:
#+begin_src emacs-lisp :exports none
  (provide 'ha-programming-clojure)
  ;;; ha-programming-clojure.el ends here
  #+end_src

#+DESCRIPTION: programming in Clojure.

#+PROPERTY:    header-args:sh :tangle no
#+PROPERTY:    header-args:emacs-lisp  :tangle yes
#+PROPERTY:    header-args    :results none :eval no-export :comments no mkdirp yes

#+OPTIONS:     num:nil toc:nil todo:nil tasks:nil tags:nil date:nil
#+OPTIONS:     skip:nil author:nil email:nil creator:nil timestamp:nil
#+INFOJS_OPT:  view:nil toc:nil ltoc:t mouse:underline buttons:0 path:http://orgmode.org/org-info.js