This service enables declarative description of doas.conf. A simple 
example would be

--8<---------------cut 
here-------------------------------------------------end--------------->8---
         (simple-service 'miscellaneous-permissions doas-service-type
                         (list (permit (identity ":wheel")
                                             (setenv `(("GUILE_LOAD_PATH" 
. #t))))
                                (permit (identity ":wheel")
                                             (nopass? #t)
                                             (command "guix")
                                             (args `("pull")))))

         (simple-service 'text-editors-permissions doas-service-type
                                  (map (lambda (cmd)
                                              (permit (identity ":wheel")
                                                          (keepenv? #t)
                                                          (command cmd)))
                                             `("kak" "emacsclient")))

         (simple-service 'power-management-permissions doas-service-type
                                  (map (lambda (cmd)
                                              (permit (identity ":wheel")
                                                           (nopass? #t)
                                                           (command cmd)
                                                           (args '())))
                                           `("zzz" "halt" "reboot")))

         (simple-service 'shepherd-status-permissions doas-service-type
                         (map (lambda (action)
                                    (permit (identity ":wheel")
                                                 (nopass? #t)
                                                 (command "herd")
                                                 (args (list action))))
                              `("status" "detailed-status")))

         (simple-service 'service-management-permissions 
doas-service-type
                         (flat-map (lambda (service action)
                                           (permit (identity ":wheel")
                                                        (nopass? #t)
                                                        (command "herd")
                                                        (args (map 
symbol->string
                                                                          
(list action service)))))
                                   '(tor networking wpa-supplicant)
                                   '(doc stop start enable status restart 
disable)))

--8<---------------cut 
here-------------------------------------------------end--------------->8---

This generates the following configuration file:

--8<---------------cut 
here-------------------------------------------------end--------------->8---

permit setenv { GUILE_LOAD_PATH }
permit nopass :wheel cmd guix args pull
permit keepenv :wheel cmd kak
permit keepenv :wheel cmd emacsclient
permit nopass :wheel cmd zzz args
permit nopass :wheel cmd halt args
permit nopass :wheel cmd reboot args
permit nopass :wheel cmd herd args status
permit nopass :wheel cmd herd args detailed-status
permit nopass :wheel cmd herd args doc tor
permit nopass :wheel cmd herd args stop tor
permit nopass :wheel cmd herd args start tor
permit nopass :wheel cmd herd args enable tor
permit nopass :wheel cmd herd args status tor
permit nopass :wheel cmd herd args restart tor
permit nopass :wheel cmd herd args disable tor
permit nopass :wheel cmd herd args doc networking
permit nopass :wheel cmd herd args stop networking
permit nopass :wheel cmd herd args start networking
permit nopass :wheel cmd herd args enable networking
permit nopass :wheel cmd herd args status networking
permit nopass :wheel cmd herd args restart networking
permit nopass :wheel cmd herd args disable networking
permit nopass :wheel cmd herd args doc wpa-supplicant
permit nopass :wheel cmd herd args stop wpa-supplicant
permit nopass :wheel cmd herd args start wpa-supplicant
permit nopass :wheel cmd herd args enable wpa-supplicant
permit nopass :wheel cmd herd args status wpa-supplicant
permit nopass :wheel cmd herd args restart wpa-supplicant
permit nopass :wheel cmd herd args disable wpa-supplicant

--8<---------------cut 
here-------------------------------------------------end--------------->8---