Minor code simplification.

Use a let binding instead of a function to destructure a tuple.

Author: sunfishcode

ml-proto/spec/eval.ml

@@ -153,8 +153,8 @@ let rec eval_expr (c : config) (e : expr) =
   | BrSwitch (_t, ec, default, labels, eo) ->
     let e = some (eval_expr c ec) ec.at in
     raise (label c
-           (try (fun (i, l) -> l)
-                (List.find (fun (i, l) -> i = e) labels)
+           (try
+              let i, l = List.find (fun (i, l) -> i = e) labels in l
             with Not_found -> default)
            (eval_expr_option c eo))