view demo/sum.ur @ 596:d1ec54288b1a

Injected a polymorphic, recursive type
author Adam Chlipala <adamc@hcoop.net>
date Thu, 08 Jan 2009 10:15:45 -0500
parents 6a0e54400805
children f4f2b09a533a
line wrap: on
line source
fun sum (fs ::: {Unit}) (x : $(mapUT int fs)) =
    foldUR [int] [fn _ => int]
    (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] n acc => n + acc)
    0 [fs] x

fun main () = return <xml><body>
  {[sum {}]}<br/>
  {[sum {A = 0, B = 1}]}<br/>
  {[sum {C = 2, D = 3, E = 4}]}
</body></xml>