diff --git a/distribution.png b/distribution.png
new file mode 100644
index 0000000..789507b
Binary files /dev/null and b/distribution.png differ
diff --git a/lib/infer_env.ml b/lib/infer_env.ml
index 4f77010..77111fb 100644
--- a/lib/infer_env.ml
+++ b/lib/infer_env.ml
@@ -6,6 +6,12 @@ type t = (Id.t, float, Id.comparator_witness) Map.t
 let empty : t = Map.empty (module Id)
 
 let add (env : t) (x : Id.t) (value : float) : t =
-  Map.add_exn env ~key:x ~data:value
+  Map.set env ~key:x ~data:value
 
 let find (env : t) (x : Id.t) : float option = Map.find env x
+
+let to_string (env : t) : string =
+  Map.to_alist env
+  |> List.map ~f:(fun (x, value) ->
+         Id.to_string x ^ " = " ^ Float.to_string value)
+  |> String.concat ~sep:", " |> Printf.sprintf "{ %s }"
diff --git a/lib/inference_runner.ml b/lib/inference_runner.ml
index 6cfb9bf..4e4f933 100644
--- a/lib/inference_runner.ml
+++ b/lib/inference_runner.ml
@@ -13,7 +13,10 @@ let eval_with_infer_env (env : Infer_env.t) (exp : Det_exp.t) : float =
     | Det_exp.Var x -> (
         match Infer_env.find env x with
         | Some value -> value
-        | None -> failwith "Variable not found in environment")
+        | None ->
+            Random.float 1.0
+            (*failwith (Printf.sprintf "Variable %s not found in environment in %s" x (Infer_env.to_string env)))*)
+        )
     | Det_exp.Add (e1, e2) -> evi ( +. ) e1 e2
     | Det_exp.Radd (e1, e2) -> evr ( +. ) e1 e2
     | Det_exp.Minus (e1, e2) -> eval env e1 -. eval env e2
diff --git a/samples/sample.stp b/samples/sample.stp
index 7799d44..75d7a60 100644
--- a/samples/sample.stp
+++ b/samples/sample.stp
@@ -1,5 +1,5 @@
 fun main() {
-  let z = sample(bernoulli(0.5+. 0.1)) in
+  let z = sample(bernoulli(0.8+. 0.1)) in
   let mu = (if (z = 0 - 0) then ~-.1.0 else 1.0) in
   let d = normal(mu, 0.0 +. 1.0) in
   let y = 0.5 in