anchor.diff:             :V-USAMPLER-BUFFER
              :V-USAMPLER-CUBE
              :V-USAMPLER-CUBE-ARRAY
  -           
  +
              ;;functions
              :TEXTURE-SIZE
              :TEXTURE
  
positive.code:            ;;definitions
             :v-defstruct
             :v-defun
             
             ;;compiler
             :varjo->glsl
  
  
negative.code:            :find-mutual-cast-type
  
             ;;environment
             :environment
             :make-varjo-environment
  
             ;;type functions
  