This shader renders white pixels but apears black window...

test.lisp

(defpackage #:test
  (:use #:cl)
  (:import-from #:cl-glfw3
                #:with-init-window
                #:def-key-callback
                #:get-proc-address
                #:set-key-callback
                #:set-window-should-close
                #:window-should-close-p
                #:swap-buffers
                #:poll-events)
  (:export #:main))
(in-package #:test)

(defparameter *context*
  (list :title "Lazy Sweet Dream"
        :version (asdf:component-version (asdf:find-system :lsd))
        :width 800
        :height 600))

(def-key-callback quit-on-escape (window key scancode action mod-keys)
  (declare (ignore window scancode mod-keys))
  (when (and (eq key :escape) (eq action :press))
    (set-window-should-close)))

(defun show-window (context)
  (with-init-window (:title (getf context :title)
                     :width (getf context :width)
                     :height (getf context :height)
                     :context-version-major 4
                     :context-version-minor 0
                     :resizable nil)
    ;; print OpenGL version
    (format t "OpenGL version: ~a.~a.~a"
            (glfw:get-window-attribute :context-version-major)
            (glfw:get-window-attribute :context-version-minor)
            (glfw:get-window-attribute :context-revision))
    (set-key-callback 'quit-on-escape)
    (glfw:swap-interval 1)

    (let* ((vs-code '(pos))
           (fs-code '((vari:vec4 1 1 1 1)))
           (vsc (varjo:translate (varjo:make-stage :vertex '((pos :vec4)) nil '(:400) vs-code)))
           (fsc (varjo:translate (varjo:make-stage :fragment '() nil '(:400) fs-code)))
           (vs (gl:create-shader :vertex-shader))
           (fs (gl:create-shader :fragment-shader))
           (p (gl:create-program)))
      (print (varjo:glsl-code vsc))
      (print (varjo:glsl-code fsc))
      (gl:shader-source vs (varjo:glsl-code vsc))
      (gl:compile-shader vs)
      (print (gl:get-shader-info-log vs))
      (gl:attach-shader p vs)

      (gl:shader-source fs (varjo:glsl-code fsc))
      (gl:compile-shader fs)
      (print (gl:get-shader-info-log fs))
      (gl:attach-shader p fs)

      (gl:bind-attrib-location p 0 "POS")
      (let ((outname (varjo:glsl-name (nth 0 (varjo:output-variables fsc)))))
        (print outname)
        (gl:bind-frag-data-location p 0 outname))

      (gl:link-program p)
      (gl:use-program p))

    (loop
      :until (window-should-close-p)
      :do (progn
            (gl:clear :color-buffer))
      :do (swap-buffers)
      :do (poll-events))))

(defun main ()
  (show-window *context*))