feat: Keep eln-cache out of my config directory.

For early-init reasons, we had to split part of syd-prelude.el out into a new
file, syd-constants.el.

users/crumb/programs/emacs/early-init.el

@@ -1,5 +1,8 @@
 ;;; early-init.el -*- lexical-binding: t; -*-
 
+(add-to-list 'load-path (file-name-concat user-emacs-directory "lib"))
+(require 'syd-constants)
+
 ;; Disable package.el; we use Straight.
 (setq package-enable-at-startup nil)
 
@@ -9,3 +12,7 @@
 (setq gc-cons-threshold
       ;; (4 gibibytes)
       (* 4 (expt 1024 3)))
+
+;; By default, Emacs will cache compilation artifacts in my personal config
+;; directory — I'm not keen on that!  Redirect it to a dedicated cache directory.
+(startup-redirect-eln-cache (file-name-concat syd-cache-dir "eln-cache"))

users/crumb/programs/emacs/init.el

@@ -9,7 +9,9 @@
 ;; Personal modules.
 
 (add-to-list 'load-path (file-name-concat user-emacs-directory "modules"))
-(add-to-list 'load-path (file-name-concat user-emacs-directory "lib"))
+
+;; Must come before the rest!
+(require 'syd-use-package)
 
 (require 'syd-age)
 (require 'syd-autosave)

users/crumb/programs/emacs/lib/syd-constants.el

@@ -0,0 +1,13 @@
+;;; syd-constants.el -*- lexical-binding: t; -*-
+
+(defvar syd-data-dir
+  (or (getenv "EMACS_DATA_DIR")
+      (error "Need $EMACS_DATA_DIR"))
+  "Directory analogous to XDG_DATA_HOME for miscellaneous Emacs things.")
+
+(defvar syd-cache-dir
+  (or (getenv "EMACS_CACHE_DIR")
+      (error "Need $EMACS_CACHE_DIR")))
+
+(provide 'syd-constants)
+;;; syd-constants.el ends here

users/crumb/programs/emacs/lib/syd-prelude.el

@@ -2,14 +2,7 @@
 
 (eval-when-compile (require 'cl-lib))
 
-(defvar syd-data-dir
+(require 'syd-constants)
-  (or (getenv "EMACS_DATA_DIR")
-      (error "Need $EMACS_DATA_DIR"))
-  "Directory analogous to XDG_DATA_HOME for miscellaneous Emacs things.")
-
-(defvar syd-cache-dir
-  (or (getenv "EMACS_CACHE_DIR")
-      (error "Need $EMACS_CACHE_DIR")))
 
 (cl-defmacro syd-define-stub
     (name &key (desc "implement me!") interactive)