annotate 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
rev   line source
adamc@412 1 fun sum (fs ::: {Unit}) (x : $(mapUT int fs)) =
adamc@411 2 foldUR [int] [fn _ => int]
adamc@411 3 (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] n acc => n + acc)
adamc@411 4 0 [fs] x
adamc@411 5
adamc@411 6 fun main () = return <xml><body>
adamc@413 7 {[sum {}]}<br/>
adamc@412 8 {[sum {A = 0, B = 1}]}<br/>
adamc@412 9 {[sum {C = 2, D = 3, E = 4}]}
adamc@411 10 </body></xml>