Rainbow Parens for 'VIP' editor

vip-rainbow.l

# Possibly the most concise implementation ever!
# 
# Parens change color everytime the screen is redrawn,
# which happens on almost every key stroke! Totally not
# distracting!
#
# INSTALL - add to '~/.pil/viprc' 

(de RAINBOW . (31 32 33 34 35 36 91 92 93 94 95 96))

(de random (L)
  (car (nth L (rand 1 (length L)))) )

(de addLine (Y L N)
   (cup (+ (: top) Y) 1)
   (clreol)
   (for C (nth L (: winX))
      (T (lt0 (dec 'N)))
      (cond
         ((: buffer flat))
         ((=T (val C))
            (ifn (>= "^_" C "^A")
               (attr NIL T)
               (setq C (char (+ 64 (char C))))
               (attr RED T) ) )
         ((>= "^_" C "^A")
            (setq C (char (+ 64 (char C))))
            (attr RED) )
         ((gt0 (val C))
            (attr CYAN) )
         ### CHANGES
         ((member C '("(" ")" "[" "]"))  # RAINBOW PARENS!!!
            (attr (random RAINBOW)) )
         ### END CHANGES
         ((= C "\"")
            (attr ULINE) )
         (T (attr)) )
      (prin C) )
   (attr) )