dotfiles/emacs/.emacs.d/config/init-lib.el

;; -*- lexical-binding: t; -*-
;; Helper packages
(use-package deferred
  :commands (deferred:next
              deferred:nextc
              deferred:error
              deferred:cancel
              deferred:watch
              deferred:wait
              deferred:$
              deferred:loop
              deferred:parallel
              deferred:earlier
              deferred:call
              deferred:apply
              deferred:process
              deferred:process-buffer
              deferred:wait-idle
              deferred:url-retrieve
              deferred:url-get
              deferred:url-post
              deferred:new
              deferred:succeed
              deferred:fail
              deferred:callback
              deferred:callback-post
              deferred:errorback
              deferred:errorback-post
              deferred:try
              deferred:timeout
              deferred:process))

(use-package s
  :defer t)

(use-package dash
  :defer t)

(use-package dash-functional
  :defer t)

(use-package f
  :defer t)

(use-package request
  :commands request)

(use-package ht
  :defer t)

;; Elisp utilities
(defun make-process-sentinel (success err)
  "Makes a process sentinel that calls `success` on success and `err` on error"
  (lambda (proc event)
    (cond ((string-match-p "finished" event) (funcall success))
	  (t (funcall err)))))

(defun make-success-err-msg-sentinel (buf success-msg err-msg &optional kill-on-err)
  (make-process-sentinel
   (lambda ()
     (message success-msg)
     (kill-buffer buf))
   (lambda ()
     (message err-msg)
     (when kill-on-err
       (kill-buffer buf)))))

(cl-defun extract-vars-from-env-file (file &key dir)
  "Extracts an alist of variable name to value from
   a bash script that exports environment variables."
  (let ((file (expand-file-name file))
	(var-re "\\(.+?\\)=\\(.+\\)$")
	(env '()))
    (with-temp-buffer
      (cd (expand-file-name (or dir (file-name-directory file))))
      (insert (shell-command-to-string (concat "source "
					       (shell-quote-argument file)
					       " > /dev/null && env")))
      (goto-char (point-min))
      (save-match-data
	(while (re-search-forward var-re nil t)
	  (push (cons (match-string 1) (match-string 2)) env))))
    env))

(defun source-env-file (file)
  (interactive "fFile: \n")
  (let ((env (extract-vars-from-env-file file)))
    (dolist (binding env)
      (setenv (car binding) (cdr binding)))))

(cl-defmacro with-env-from-file (file &rest body)
  (declare (indent 1))
  (let ((env-var (make-symbol "the-env"))
	(path-var (make-symbol "the-path")))
    `(let* ((,env-var (extract-vars-from-env-file ,file))
	    (,path-var (assoc "PATH" ,env-var))
	    (exec-path
	     (if ,path-var
		 (append (split-string (cdr ,path-var) ":") exec-path)
	       exec-path))
	    (process-environment
	     (append
	      (mapcar
	       (lambda (elt) (format "%s=%s" (car elt) (cdr elt)))
	       ,env-var)
	      process-environment)))
       ,@body)))

(cl-defun call-with-env-from-file (file callback &key dir)
  (let* ((env (extract-vars-from-env-file file :dir dir))
	 (path (assoc "PATH" env))
	 (exec-path
	  (if path
	      (append (split-string (cdr path) ":") exec-path)
	    exec-path))
	 (process-environment
	  (append (mapcar (lambda (elt) (format "%s=%s" (car elt) (cdr elt))) env)
		  process-environment)))
    (funcall callback)))

(defmacro with-env (env &rest body)
  (declare (indent 1))
  `(let* ((process-environment
	   (append
	    (mapcar
	     (lambda (elt) (format "%s=%s" (car elt) (cdr elt)))
	     ,env)
	    process-environment)))
     ,@body))

(provide 'init-lib)