From dbe3c6c203b935e1fe355219c9ff4a3e469200bc Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 8 May 2026 16:11:03 +0000
Subject: [PATCH] ocaml: phase 5.1 word_count.ml baseline (10/10 pass)

Uses Map.Make(StrOrd) + List.fold_left to count word frequencies;
exercises the full functor pipeline with a real-world idiom:

  let inc_count m word =
    match StrMap.find_opt word m with
    | None -> StrMap.add word 1 m
    | Some n -> StrMap.add word (n + 1) m
  let count words = List.fold_left inc_count StrMap.empty words

10/10 baseline programs pass.
---
 lib/ocaml/baseline/expected.json |  3 ++-
 lib/ocaml/baseline/word_count.ml | 14 ++++++++++++++
 plans/ocaml-on-sx.md             |  3 +++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 lib/ocaml/baseline/word_count.ml

diff --git a/lib/ocaml/baseline/expected.json b/lib/ocaml/baseline/expected.json
index 4d328b0d..3452637e 100644
--- a/lib/ocaml/baseline/expected.json
+++ b/lib/ocaml/baseline/expected.json
@@ -7,5 +7,6 @@
   "module_use.ml": 3,
   "option_match.ml": 5,
   "quicksort.ml": 44,
-  "sum_squares.ml": 385
+  "sum_squares.ml": 385,
+  "word_count.ml": 3
 }
diff --git a/lib/ocaml/baseline/word_count.ml b/lib/ocaml/baseline/word_count.ml
new file mode 100644
index 00000000..d455225e
--- /dev/null
+++ b/lib/ocaml/baseline/word_count.ml
@@ -0,0 +1,14 @@
+(* Baseline: word-frequency map over a list using Map.Make + List.fold_left *)
+module StrOrd = struct let compare a b = compare a b end ;;
+module StrMap = Map.Make(StrOrd) ;;
+
+let inc_count m word =
+  match StrMap.find_opt word m with
+  | None -> StrMap.add word 1 m
+  | Some n -> StrMap.add word (n + 1) m
+;;
+
+let count words = List.fold_left inc_count StrMap.empty words ;;
+
+let m = count ["the"; "fox"; "the"; "dog"; "the"; "fox"] ;;
+StrMap.find "the" m
diff --git a/plans/ocaml-on-sx.md b/plans/ocaml-on-sx.md
index bc10a8fb..b44bcece 100644
--- a/plans/ocaml-on-sx.md
+++ b/plans/ocaml-on-sx.md
@@ -386,6 +386,9 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-08 Phase 5.1 — word_count.ml baseline (10/10 pass). Uses
+  Map.Make(StrOrd) + List.fold_left to count word frequencies; tests
+  the full functor pipeline with a real OCaml idiom.
 - 2026-05-08 Phase 6 — Map/Set extensions: iter/fold/map/filter/
   is_empty + Set.union/inter (+4 tests, 422 total). Functor
   bodies grow naturally — all in OCaml syntax.