wip: feat: Just use straight.el...

Every Nixy solution I could find or conceive had too many points spread across
these various facets:
  - Flimsy (emacsWithPackagesFromUsePackage)
  - Inelegant (builtins.exec, manual listings)
  - Inflexible (emacsWithPackagesFromUsePackage)
  - Otherwise unergonomic (everything }:D)

Straight.el is sufficiently declarative, flexible, and Nix-friendly without
blindly bowing down to the imperialist NixOS user.  Now, Convenience and
ergonomics shan't be forsaken for the dogma that is total Nixation.

users/crumb/programs/emacs/init.el

@@ -1,6 +1,32 @@
 ;; -*- lexical-binding: t; -*-
 
-(require 'use-package-ensure)
-(setq use-package-always-ensure t)
+(defvar bootstrap-version)
 
-(use-package evil)
+(setq straight-base-dir
+      (or (getenv "EMACS_STRAIGHT_BASE_DIR")
+          (error "Cannot initialise straight: $EMACS_STRAIGHT_BASE_DIR is undefined!")))
+
+(let ((bootstrap-file
+       (file-name-concat straight-base-dir
+                         "repos/straight.el/bootstrap.el"))
+      (bootstrap-version 7))
+  (unless (file-exists-p bootstrap-file)
+    (let* ((url "https://raw.githubusercontent.com/radian-software/straight.el/develop/install.el")
+           (url-buffer (url-retrieve-synchronously
+                        url 'silent 'inhibit-cookies)))
+      (with-current-buffer url-buffer
+        (goto-char (point-max))
+        (eval-print-last-sexp))))
+  (load bootstrap-file nil 'nomessage))
+
+(setq straight-use-package-by-default t)
+
+(use-package evil
+  :init
+  (setq evil-want-minibuffer t)
+  :config
+  (evil-mode 1))
+
+(use-package which-key
+  :config
+  (which-key-mode 1))