start adding mixture function

ocaml/samples.ml

@@ -2,6 +2,17 @@
 let pi = acos (-1.)
 let normal_95_ci_length = 1.6448536269514722
 
+(* Array manipulation helpers *)
+let sumFloats xs = List.fold_left(fun acc x -> acc +. x) 0.0 xs
+let normalizeXs xs = let sum_xs = sumFloats xs in 
+  List.map(fun x -> x /. sum_xs) xs
+let cumsumXs xs = 
+  let _, cum_sum = List.fold_left(fun (sum, ys) x -> 
+    let new_sum = sum +. x in
+    new_sum, ys @ [new_sum]
+  ) (0.0, []) xs in
+  cum_sum
+
 (* Basic samplers *)
 let sampleZeroToOne () : float = Random.float 1.0
 let sampleStandardNormal (): float = 
@@ -17,6 +28,11 @@ let sampleTo low high =
   let logmean = (loglow +. loghigh) /. 2.0 in
   let logstd = (loghigh -. loglow) /. (2.0 -. normal_95_ci_length ) in
   sampleLognormal logmean logstd
+let mixture (samplers: (unit -> float) list) (weights: float list) = 
+  match (List.length samplers == List.length weights) with
+    | false -> None
+    | true -> let normalized_weights = cumsumXs (normalizeXs weights) in Some(1.0)
+      
 
 let () =
   Random.init 1;