let mem e s = ((1 lsl e) land s) != 0
let add e s = (1 lsl e) lor s
let singleton e = (1 lsl e)
- let union = (lor)
- let inter = (land)
+ let union a b = a lor b
+ let inter a b = a land b
let diff a b = a land (lnot b)
let remove e s = (lnot (1 lsl e) land s)
let compare = (-)