ocaml: phase 5.1 max_run.ml baseline (longest consecutive run, 4+1+0 = 5)

Walks list keeping a previous-value reference; increments cur on
match, resets to 1 otherwise. Uses 'Some y when y = x' guard pattern
in match for the prev-value comparison:

  let max_run xs =
    let max_so_far = ref 0 in
    let cur = ref 0 in
    let last = ref None in
    List.iter (fun x ->
      (match !last with
       | Some y when y = x -> cur := !cur + 1
       | _ -> cur := 1);
      last := Some x;
      if !cur > !max_so_far then max_so_far := !cur
    ) xs;
    !max_so_far

Three test cases:
  [1;1;2;2;2;2;3;3;1;1;1]   max run = 4 (the 2's)
  [1;2;3;4;5]                max run = 1
  []                          max run = 0
  sum = 5

Tests 'when' guard pattern in match arm + Option ref + ref-mutation
sequence inside List.iter closure body.

94 baseline programs total.

lib/ocaml/baseline/expected.json

@@ -44,6 +44,7 @@
   "luhn.ml": 2,
   "mat_mul.ml": 621,
   "max_path_tree.ml": 11,
+  "max_run.ml": 5,
   "mod_inverse.ml": 27,
   "json_pretty.ml": 24,
   "kadane.ml": 6,

lib/ocaml/baseline/max_run.ml

@@ -0,0 +1,16 @@
+let max_run xs =
+  let max_so_far = ref 0 in
+  let cur = ref 0 in
+  let last = ref None in
+  List.iter (fun x ->
+    (match !last with
+     | Some y when y = x -> cur := !cur + 1
+     | _ -> cur := 1);
+    last := Some x;
+    if !cur > !max_so_far then max_so_far := !cur
+  ) xs;
+  !max_so_far
+
+;;
+
+max_run [1;1;2;2;2;2;3;3;1;1;1] + max_run [1;2;3;4;5] + max_run []