add CCFloat.round

src/core/CCFloat.ml

@@ -60,6 +60,17 @@ let sign_exn (a:float) =
   if is_nan a then raise (TrapNaN "sign_exn")
   else compare a 0.
 
+let round x =
+  let low = floor x in
+  let high = ceil x in
+  if x-.low > high-.x then high else low
+
+(*$=
+  2. (round 1.6)
+  1. (round 1.4)
+  0. (round 0.)
+*)
+
 let to_int (a:float) = Pervasives.int_of_float a
 let of_int (a:int) = Pervasives.float_of_int a
 

src/core/CCFloat.mli

@@ -58,6 +58,10 @@ val fsign : t -> t
 (** [fsign x] is one of [-1., -0., +0., +1.], or [nan] if [x] is NaN.
     @since 0.7 *)
 
+val round : t -> t
+(** [round f] returns the closest integer value, either above or below
+    @since NEXT_RELEASE *)
+
 exception TrapNaN of string
 val sign_exn : t -> int
 (** [sign_exn x] will return the sign of [x] as [1, 0] or [-1], or raise an