Lisp error: (void-variable comint-mode-map)

gistfile1.txt

;;; REPL
;; Setting up, creating the gjs-repl window, and starting the gjs
;; shell. These tasks are currently being performed by js-comint.

(defvar gjs-file-path "/usr/bin/gjs"
  "Path to the program used by `run-gjs'")
 
(defvar gjs-arguments '()
  "Commandline arguments to pass to `gjs'")
 

preliminaries^^^^-------------------------------------------

(defvar gjs-mode-map
   (let ((map (nconc (make-sparse-keymap) comint-mode-map)))
     ;; example definition
     (define-key map "\t" 'completion-at-point)
     map)
   "Basic mode map for `run-gjs'")



Debugger entered--Lisp error: (void-variable comint-mode-map)
  (nconc (make-sparse-keymap) comint-mode-map)
  (let ((map (nconc (make-sparse-keymap) comint-mode-map))) (define-key map "	" (quote completion-at-point)) map)
  (defvar gjs-mode-map (let ((map (nconc (make-sparse-keymap) comint-mode-map))) (define-key map "	" (quote completion-at-point)) map) "Basic mode map for `run-gjs'")
  eval((defvar gjs-mode-map (let ((map (nconc (make-sparse-keymap) comint-mode-map))) (define-key map "	" (quote completion-at-point)) map) "Basic mode map for `run-gjs'") nil)
  eval-last-sexp-1(nil)
  eval-last-sexp(nil)
  call-interactively(eval-last-sexp nil nil)

oh. (require 'comint) is required