ocaml: phase 6 Bool module + Option.equal/Option.compare (+5 tests, 584 total)

Bool module:
  equal a b      = a = b
  compare a b    = 0 if equal, 1 if a, -1 if b (false < true)
  to_string      'true' / 'false'
  of_string s    = s = 'true'
  not_           wraps host not
  to_int         true=1, false=0

Option additions (take eq/cmp parameter for the inner value):
  equal eq a b   None=None, otherwise eq the inner values
  compare cmp a b  None < Some _; otherwise cmp inner

  Option.equal (=) (Some 1) (Some 1)        = true
  Option.equal (=) (Some 1) None             = false
  Option.compare compare (Some 5) (Some 3)  = 1

plans/ocaml-on-sx.md

@@ -407,6 +407,12 @@ _Newest first._
   binary search tree (`type 'a tree = Leaf | Node of 'a * 'a tree *
   'a tree`) with insert + in-order traversal. Tests parametric ADT,
   recursive match, List.append, List.fold_left.
+- 2026-05-09 Phase 6 — Bool module + Option.equal / Option.compare
+  (+5 tests, 584 total). Bool: equal, compare (false < true via if
+  ladder), to_string, of_string, not_, to_int. Option additions
+  take an `eq` or `cmp` parameter for the inner-value check, mirroring
+  real OCaml's signature: `Option.equal eq a b`, `Option.compare cmp
+  a b`. None < Some _ for compare.
 - 2026-05-09 Phase 5.1 — bag.ml baseline + String.equal/compare/cat/
   empty (+3 tests, 579 total). bag.ml: split a sentence on spaces,
   count word frequency in a Hashtbl, return the maximum count.