terminal:
user@host ~$ sudo guix system reconfigure /etc/config.scm
/etc/config.scm:37:19: error: user: unbound variable
hint: Did you forget a `use-modules' form?


/etc/config.scm:
;; This is an operating system configuration generated
;; by the graphical installer.

(use-modules (gnu))
(use-service-modules desktop networking ssh xorg)
(use-package-modules xorg)
(use-modules (nongnu packages linux)
             (nongnu system linux-initrd))
(use-modules (srfi srfi-1))  ;for 'remove'

(operating-system
  (kernel linux)
  (initrd microcode-initrd)
  (firmware (cons* iwlwifi-firmware
                   amdgpu-firmware
                   %base-firmware))
  (locale "en_US.utf8")
  (timezone "America/New_York")
  (keyboard-layout (keyboard-layout "us"))
  (host-name "host")
  (users (cons* (user-account
                  (name "user")
                  (comment "user")
                  (group "users")
                  (home-directory "/home/user")
                  (supplementary-groups
                    '("wheel" "netdev" "audio" "video")))
                %base-user-accounts))
  (packages
    (append
      (list (specification->package "i3-wm")
            (specification->package "i3status")
            (specification->package "dmenu")
            (specification->package "st")
            (specification->package "nss-certs"))
      %base-packages))
  (services (cons* (set-xorg-configuration
                    (xorg-configuration
                     (extra-config
		 '("
                   Section \"InputClass\"
                    Identifier \"My Mouse\"
                    Driver \"libinput\"
                    MatchIsPointer \"yes\"
                    Option \"AccelProfile\" \"flat\"
                    Option \"AccelSpeed\" \"0\"
                   EndSection
                   Section \"Device\"
                     Identifier  \"AMD\"
                     Driver      \"amdgpu\"
                     Option      \"VariableRefresh\" \"true\"
                   EndSection
		   Section \"Monitor\"
                    Identifier \"DisplayPort-3\"
                    Modeline \"1920x1080_144\" 325.08  1920 1944 1976 2056  1080 1083 1088 1098 +hsync +vsync
                    Option \"PreferredMode\" \"1920x1080_144\"
                    Option \"Primary\" \"true\"
                   EndSection
                   Section \"Monitor\"
                    Identifier \"DVI-D-0\"
                    Option \"Primary\" \"false\"
                    Option \"RightOf\" \"DisplayPort-3\"
                   EndSection
                   "))))
		   (service slim-service-type (slim-configuration
                                               (display ":0")
                                               (vt "vt7")
                                               (auto-login-session #t)
                                               (default-user user)))
;;; a second SLiM on another vt
;;                 (service slim-service-type (slim-configuration
;;                                             (display ":1")
;;                                             (vt "vt8")))
                   (remove (lambda (service)
                             (eq? (service-kind service) gdm-service-type))
                           %desktop-services)))
  (bootloader
    (bootloader-configuration
      (bootloader grub-efi-bootloader)
      (target "/boot/efi")
      (keyboard-layout keyboard-layout)))
  (mapped-devices
    (list (mapped-device
            (source
              (uuid "71815e69-0568-4dc3-897f-186c77df1ce4"))
            (target "cryptroot")
            (type luks-device-mapping))))
  (file-systems
    (cons* (file-system
             (mount-point "/boot/efi")
             (device (uuid "7CE9-38DB" 'fat32))
             (type "vfat"))
           (file-system
             (mount-point "/")
             (device "/dev/mapper/cryptroot")
             (type "ext4")
             (dependencies mapped-devices))
           %base-file-systems)))