view demo/tcSum.ur @ 723:311ca1ae715d

Simplify type class requirement for tree demo
author Adam Chlipala <adamc@hcoop.net>
date Mon, 13 Apr 2009 08:44:32 -0400
parents aa2290c32ce2
children 669ac5e9a69e
line wrap: on
line source
fun sum (t ::: Type) (_ : num t) (fs ::: {Unit}) (fl : folder fs) (x : $(mapU t fs)) =
    foldUR [t] [fn _ => t]
    (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] n acc => n + acc)
    zero [fs] fl x

fun main () = return <xml><body>
  {[sum {A = 0, B = 1}]}<br/>
  {[sum {C = 2.1, D = 3.2, E = 4.3}]}
</body></xml>