[Emacs] Rename eshell/my-prompt', simplify phundrak/abbr-pwd'

This commit renames `eshell/my-prompt' to `phundrak/eshell-prompt'.

`phundrak/abbr-pwd' is now simplified, and it is no longer responsible
for fetching the current path which must now be passed as its first
argument. It will also reject any argument which is neither a string
(should be the only type to be passed for public use) nor a list (for
internal usage).

org/config/emacs.org

@@ -1404,22 +1404,22 @@
     path, but  leaves the current one  written in full. It  also abbreviates the
     equivalent of the ~$HOME~ (~/home/<username>/~) directory to a simple =~=.
     #+BEGIN_SRC emacs-lisp
-      (defun phundrak/abbr-pwd (&optional $abbreviate $path $abbreviating)
+      (defun phundrak/abbr-pwd ($path &optional $abbreviate)
         (cond
-         ((and (null $path)
-               $abbreviating) "")
-         ((and $abbreviate
-               (= 1 (length $path)))
-          (car $path))
-         ((and $abbreviate $path)
-          (f-join (let* ((dir (car $path))
+         ((stringp $path) (f-short
+                           (if $abbreviate
+                               (phundrak/abbr-pwd (f-split (abbr-pwd $path)))
+                             $path)))
+         ((null $path) "")
+         ((listp $path)
+          (f-join (cond ((= 1 (length $path)) (car $path))
+                        (t (let* ((dir (car $path))
                                   (first-char (s-left 1 dir)))
                              (if (string= "." first-char)
                                  (s-left 2 dir)
-                      first-char))
-                  (phundrak/abbr-pwd t (cdr $path) t)))
-         ($abbreviate (f-short (phundrak/abbr-pwd t (f-split (phundrak/abbr-pwd)))))
-         (t (f-short (eshell/pwd)))))
+                               first-char))))
+                  (phundrak/abbr-pwd (cdr $path))))
+         (t (error "Invalid argument %s, neither stringp nor listp" $path))))
     #+END_SRC
 
 *** ~phundrak/prompt-toggle-abbreviation~
@@ -1965,7 +1965,7 @@
      is ~t~ it is abbreviated; otherwise, it is kept in full. It can be toggled
      with a keyboard shortcut, see [[#User_Configuration-Shortcuts-Toggle-d53c27ef][Keybindings: Toggle]].
      #+BEGIN_SRC emacs-lisp
-       (defun eshell/my-prompt ()
+       (defun phundrak/eshell-prompt ()
          "Definition of my prompt for Eshell
 
        It displays a powerline prompt, with first an abbreviated path to
@@ -1983,8 +1983,8 @@
        red depending on if the last eshell command was a success or a
        failure respectively."
          (let* ((header-bg  phundrak/nord0)
-                ($path      (phundrak/abbr-pwd))
-                ($abbr-path (phundrak/abbr-pwd phundrak/prompt--abbreviate))
+                ($path      (phundrak/abbr-pwd (eshell/pwd)))
+                ($abbr-path (phundrak/abbr-pwd $path phundrak/prompt--abbreviate))
                 ($background phundrak/nord1))
            (concat (with-face " " :background $background)
                    (with-face $abbr-path
@@ -2008,7 +2008,7 @@
      Now, let’s declare our prompt regexp and our prompt functions:
      #+BEGIN_SRC emacs-lisp
        (setq eshell-prompt-regexp "^[^#$\n]*[#$] "
-             eshell-prompt-function 'eshell/my-prompt)
+             eshell-prompt-function 'phundrak/eshell-prompt)
      #+END_SRC
 
 *** Org-mode