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structure Bug =
struct
structure F = MLton.Finalizable
fun new_t () =
let
val p = 0
val t = F.new p
fun finalize x = ()
in
F.addFinalizer(t,finalize);
t
end
fun from_string (_:string) =
let
val x = new_t ()
in
F.withValue(x,fn p => ());
x
end
val zero = from_string "0.0"
(* NOTE: I removed the F.withValue lines in an attempt to make the
code simpler, but the bug didn't manifest itself. So I think these
lines are critical. *)
fun plus (x,y) =
let
val z = new_t ()
in
F.withValue(x,fn xp =>
F.withValue(y,fn yp =>
F.withValue(z,fn zp =>
let in
z
end)))
end
end
structure B = Bug
fun bigsum (n,store) =
if n = 0 then store else
let
val _ = if Int.mod(n,10000) = 0 then print (Int.toString n ^ "\n") else ()
in
bigsum(Int.-(n,1),B.plus(store,B.from_string(Int.toString n ^ ".0")))
end
val bigsum = (fn n => bigsum(n,B.zero))
val x = bigsum 5000000
|
