From 19f1cad11dd532c53258af309493232f4ea4b427 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 8 May 2026 08:49:44 +0000
Subject: [PATCH] ocaml: phase 6 stdlib slice (List/Option/Result, +23 tests,
 248 total)
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lib/ocaml/runtime.sx defines the stdlib in OCaml syntax (not SX): every
function exercises the parser, evaluator, match engine, and module
machinery built in earlier phases. Loaded once via ocaml-load-stdlib!,
cached in ocaml-stdlib-env, layered under user code via ocaml-base-env.

List: length, rev, rev_append, map, filter, fold_left/right, append,
iter, mem, for_all, exists, hd, tl, nth.
Option: map, bind, value, get, is_none, is_some.
Result: map, bind, is_ok, is_error.

Substrate validation: this stdlib is a nontrivial OCaml program — its
mere existence proves the substrate works.
---
 lib/ocaml/eval.sx    |  18 ++++-
 lib/ocaml/runtime.sx | 173 +++++++++++++++++++++++++++++++++++++++++++
 lib/ocaml/test.sh    |  82 ++++++++++++++++++++
 plans/ocaml-on-sx.md |  26 +++++--
 4 files changed, 288 insertions(+), 11 deletions(-)
 create mode 100644 lib/ocaml/runtime.sx

diff --git a/lib/ocaml/eval.sx b/lib/ocaml/eval.sx
index 873b391f..ddbfdd01 100644
--- a/lib/ocaml/eval.sx
+++ b/lib/ocaml/eval.sx
@@ -588,16 +588,28 @@
         (loop decls)
         result))))
 
-;; ocaml-run — convenience wrapper: parse + eval.
+;; ocaml-run — convenience wrapper: parse + eval. Layers the stdlib env
+;; (List, Option, Result) underneath the empty env so user code can use
+;; `List.map` etc. without explicit setup.
+;; Variable guarded so eval.sx is loadable without runtime.sx. runtime.sx
+;; sets ocaml-stdlib-env once loaded; before that, fall back to the empty
+;; env so the existing tests continue to work without stdlib.
+(define ocaml-stdlib-env nil)
+(define ocaml-base-env
+  (fn ()
+    (cond
+      ((not (= ocaml-stdlib-env nil)) ocaml-stdlib-env)
+      (else (ocaml-empty-env)))))
+
 (define ocaml-run
   (fn (src)
-    (ocaml-eval (ocaml-parse src) (ocaml-empty-env))))
+    (ocaml-eval (ocaml-parse src) (ocaml-base-env))))
 
 ;; ocaml-run-program — evaluate a program (sequence of decls + bare exprs).
 ;; Threads an env through decls; returns the value of the last form.
 (define ocaml-run-program
   (fn (src)
-    (let ((prog (ocaml-parse-program src)) (env (ocaml-empty-env)) (last nil))
+    (let ((prog (ocaml-parse-program src)) (env (ocaml-base-env)) (last nil))
       (begin
         (define run-decl
           (fn (decl)
diff --git a/lib/ocaml/runtime.sx b/lib/ocaml/runtime.sx
new file mode 100644
index 00000000..47b8bbb5
--- /dev/null
+++ b/lib/ocaml/runtime.sx
@@ -0,0 +1,173 @@
+;; lib/ocaml/runtime.sx — minimal OCaml stdlib slice, written in OCaml.
+;;
+;; Defines List and Option modules with the most-used functions. Loaded
+;; on demand via `(ocaml-load-stdlib! env)` from eval.sx, which parses
+;; this source through `ocaml-parse-program` and evaluates each decl,
+;; threading the env so stdlib bindings become available to user code.
+;;
+;; What's here is intentionally minimal — Phase 6 grows this into the
+;; full ~150-function slice. Everything is defined in OCaml syntax (not
+;; SX) on purpose, both as substrate validation and as documentation.
+
+(define ocaml-stdlib-src
+  "module List = struct
+     let rec length lst =
+       match lst with
+       | [] -> 0
+       | _ :: t -> 1 + length t
+
+     let rec rev_append xs acc =
+       match xs with
+       | [] -> acc
+       | h :: t -> rev_append t (h :: acc)
+
+     let rev xs = rev_append xs []
+
+     let rec map f lst =
+       match lst with
+       | [] -> []
+       | h :: t -> f h :: map f t
+
+     let rec filter p lst =
+       match lst with
+       | [] -> []
+       | h :: t -> if p h then h :: filter p t else filter p t
+
+     let rec fold_left f init lst =
+       match lst with
+       | [] -> init
+       | h :: t -> fold_left f (f init h) t
+
+     let rec fold_right f lst init =
+       match lst with
+       | [] -> init
+       | h :: t -> f h (fold_right f t init)
+
+     let rec append xs ys =
+       match xs with
+       | [] -> ys
+       | h :: t -> h :: append t ys
+
+     let rec iter f lst =
+       match lst with
+       | [] -> ()
+       | h :: t -> f h; iter f t
+
+     let rec mem x lst =
+       match lst with
+       | [] -> false
+       | h :: t -> if h = x then true else mem x t
+
+     let rec for_all p lst =
+       match lst with
+       | [] -> true
+       | h :: t -> if p h then for_all p t else false
+
+     let rec exists p lst =
+       match lst with
+       | [] -> false
+       | h :: t -> if p h then true else exists p t
+
+     let hd lst =
+       match lst with
+       | [] -> failwith \"List.hd: empty\"
+       | h :: _ -> h
+
+     let tl lst =
+       match lst with
+       | [] -> failwith \"List.tl: empty\"
+       | _ :: t -> t
+
+     let rec nth lst n =
+       match lst with
+       | [] -> failwith \"List.nth: out of range\"
+       | h :: t -> if n = 0 then h else nth t (n - 1)
+   end ;;
+
+   module Option = struct
+     let map f o =
+       match o with
+       | None -> None
+       | Some x -> Some (f x)
+
+     let bind o f =
+       match o with
+       | None -> None
+       | Some x -> f x
+
+     let value o default =
+       match o with
+       | None -> default
+       | Some x -> x
+
+     let get o =
+       match o with
+       | None -> failwith \"Option.get: None\"
+       | Some x -> x
+
+     let is_none o =
+       match o with
+       | None -> true
+       | Some _ -> false
+
+     let is_some o =
+       match o with
+       | None -> false
+       | Some _ -> true
+   end ;;
+
+   module Result = struct
+     let map f r =
+       match r with
+       | Ok x -> Ok (f x)
+       | Error e -> Error e
+
+     let bind r f =
+       match r with
+       | Ok x -> f x
+       | Error e -> Error e
+
+     let is_ok r =
+       match r with
+       | Ok _ -> true
+       | Error _ -> false
+
+     let is_error r =
+       match r with
+       | Ok _ -> false
+       | Error _ -> true
+   end")
+
+(define ocaml-stdlib-loaded false)
+(define ocaml-stdlib-env nil)
+
+;; Build a stdlib env once, cache it. ocaml-run / ocaml-run-program both
+;; layer the user program on top of this base env.
+(define ocaml-load-stdlib!
+  (fn ()
+    (when (not ocaml-stdlib-loaded)
+      (let ((env (ocaml-empty-env)))
+        (begin
+          (define run-decl
+            (fn (decl)
+              (let ((tag (ocaml-tag-of decl)))
+                (cond
+                  ((= tag "module-def")
+                    (let ((mn (nth decl 1)) (ds (nth decl 2)))
+                      (let ((mv (ocaml-eval-module ds env)))
+                        (set! env (ocaml-env-extend env mn mv)))))
+                  ((= tag "def")
+                    (let ((nm (nth decl 1)) (ps (nth decl 2)) (rh (nth decl 3)))
+                      (let ((v (if (= (len ps) 0)
+                                   (ocaml-eval rh env)
+                                   (ocaml-make-curried ps rh env))))
+                        (set! env (ocaml-env-extend env nm v)))))))))
+          (let ((prog (ocaml-parse-program ocaml-stdlib-src)))
+            (begin
+              (define loop
+                (fn (xs)
+                  (when (not (= xs (list)))
+                    (begin (run-decl (first xs)) (loop (rest xs))))))
+              (loop (rest prog))
+              (set! ocaml-stdlib-env env)
+              (set! ocaml-stdlib-loaded true))))))))
diff --git a/lib/ocaml/test.sh b/lib/ocaml/test.sh
index 98937c07..261f6dea 100755
--- a/lib/ocaml/test.sh
+++ b/lib/ocaml/test.sh
@@ -33,7 +33,9 @@ cat > "$TMPFILE" << 'EPOCHS'
 (load "lib/ocaml/tokenizer.sx")
 (load "lib/ocaml/parser.sx")
 (load "lib/ocaml/eval.sx")
+(load "lib/ocaml/runtime.sx")
 (load "lib/ocaml/tests/tokenize.sx")
+(eval "(ocaml-load-stdlib!)")
 
 ;; ── empty / eof ────────────────────────────────────────────────
 (epoch 100)
@@ -579,6 +581,56 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 754)
 (eval "(ocaml-run-program \"module Identity (M) = struct include M end ;; module Base = struct let v = 99 end ;; module Same = Identity(Base) ;; Same.v\")")
 
+;; ── Phase 6: stdlib slice (List, Option, Result) ───────────────
+(epoch 800)
+(eval "(ocaml-run \"List.length [1; 2; 3; 4]\")")
+(epoch 801)
+(eval "(ocaml-run \"List.length []\")")
+(epoch 802)
+(eval "(ocaml-run \"List.map (fun x -> x * 2) [1; 2; 3]\")")
+(epoch 803)
+(eval "(ocaml-run \"List.filter (fun x -> x > 2) [1; 2; 3; 4; 5]\")")
+(epoch 804)
+(eval "(ocaml-run \"List.fold_left (fun a b -> a + b) 0 [1; 2; 3; 4; 5]\")")
+(epoch 805)
+(eval "(ocaml-run \"List.fold_right (fun x acc -> x :: acc) [1; 2; 3] []\")")
+(epoch 806)
+(eval "(ocaml-run \"List.rev [1; 2; 3]\")")
+(epoch 807)
+(eval "(ocaml-run \"List.append [1; 2] [3; 4]\")")
+(epoch 808)
+(eval "(ocaml-run \"List.mem 3 [1; 2; 3]\")")
+(epoch 809)
+(eval "(ocaml-run \"List.mem 99 [1; 2; 3]\")")
+(epoch 810)
+(eval "(ocaml-run \"List.for_all (fun x -> x > 0) [1; 2; 3]\")")
+(epoch 811)
+(eval "(ocaml-run \"List.exists (fun x -> x > 2) [1; 2; 3]\")")
+(epoch 812)
+(eval "(ocaml-run \"List.hd [10; 20; 30]\")")
+(epoch 813)
+(eval "(ocaml-run \"List.nth [10; 20; 30] 1\")")
+
+(epoch 820)
+(eval "(ocaml-run \"Option.map (fun x -> x + 1) (Some 41)\")")
+(epoch 821)
+(eval "(ocaml-run \"Option.map (fun x -> x + 1) None\")")
+(epoch 822)
+(eval "(ocaml-run \"Option.value (Some 7) 0\")")
+(epoch 823)
+(eval "(ocaml-run \"Option.value None 42\")")
+(epoch 824)
+(eval "(ocaml-run \"Option.is_some (Some 1)\")")
+(epoch 825)
+(eval "(ocaml-run \"Option.is_none None\")")
+
+(epoch 830)
+(eval "(ocaml-run \"Result.map (fun x -> x + 1) (Ok 5)\")")
+(epoch 831)
+(eval "(ocaml-run \"Result.is_ok (Ok 1)\")")
+(epoch 832)
+(eval "(ocaml-run \"Result.is_error (Error \\\"oops\\\")\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -921,6 +973,36 @@ check 752 "submodule alias"              '42'
 check 753 "multi-param functor"          '("tuple" 1 2)'
 check 754 "Identity functor + include"   '99'
 
+# ── Phase 6: stdlib slice ───────────────────────────────────────
+# List
+check 800 "List.length [1..4]"           '4'
+check 801 "List.length []"               '0'
+check 802 "List.map x*2 [1;2;3]"         '(2 4 6)'
+check 803 "List.filter > 2"              '(3 4 5)'
+check 804 "List.fold_left + 0 [1..5]"    '15'
+check 805 "List.fold_right ::"           '(1 2 3)'
+check 806 "List.rev"                     '(3 2 1)'
+check 807 "List.append"                  '(1 2 3 4)'
+check 808 "List.mem 3"                   'true'
+check 809 "List.mem 99"                  'false'
+check 810 "List.for_all >0"              'true'
+check 811 "List.exists >2"               'true'
+check 812 "List.hd"                      '10'
+check 813 "List.nth idx 1"               '20'
+
+# Option
+check 820 "Option.map Some"              '("Some" 42)'
+check 821 "Option.map None"              '("None")'
+check 822 "Option.value Some"            '7'
+check 823 "Option.value None"            '42'
+check 824 "Option.is_some"               'true'
+check 825 "Option.is_none"               'true'
+
+# Result
+check 830 "Result.map Ok"                '("Ok" 6)'
+check 831 "Result.is_ok"                 'true'
+check 832 "Result.is_error"              'true'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"
diff --git a/plans/ocaml-on-sx.md b/plans/ocaml-on-sx.md
index 8e428a17..2d76261f 100644
--- a/plans/ocaml-on-sx.md
+++ b/plans/ocaml-on-sx.md
@@ -215,14 +215,14 @@ SX CEK evaluator (both JS and OCaml hosts)
 
 ### Phase 6 — Standard library
 
-- [ ] `List`: `map`, `filter`, `fold_left`, `fold_right`, `length`, `rev`, `append`,
-      `concat`, `flatten`, `iter`, `iteri`, `mapi`, `for_all`, `exists`, `find`,
-      `find_opt`, `mem`, `assoc`, `assq`, `sort`, `stable_sort`, `nth`, `hd`, `tl`,
-      `init`, `combine`, `split`, `partition`.
-- [ ] `Option`: `map`, `bind`, `fold`, `get`, `value`, `join`, `iter`, `to_list`,
-      `to_result`, `is_none`, `is_some`.
-- [ ] `Result`: `map`, `bind`, `fold`, `get_ok`, `get_error`, `map_error`,
-      `to_option`, `is_ok`, `is_error`.
+- [~] `List`: `map`, `filter`, `fold_left`, `fold_right`, `length`, `rev`,
+      `append`, `iter`, `for_all`, `exists`, `mem`, `nth`, `hd`, `tl`,
+      `rev_append`. _(Pending: concat/flatten, iteri/mapi, find/find_opt,
+      assoc/assq, sort, init, combine, split, partition.)_
+- [~] `Option`: `map`, `bind`, `value`, `get`, `is_none`, `is_some`.
+      _(Pending: fold/join/iter/to_list/to_result.)_
+- [~] `Result`: `map`, `bind`, `is_ok`, `is_error`. _(Pending:
+      fold/get_ok/get_error/map_error/to_option.)_
 - [ ] `String`: `length`, `get`, `sub`, `concat`, `split_on_char`, `trim`,
       `uppercase_ascii`, `lowercase_ascii`, `contains`, `starts_with`, `ends_with`,
       `index_opt`, `replace_all` (non-stdlib but needed).
@@ -327,6 +327,16 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-08 Phase 6 — `lib/ocaml/runtime.sx` minimal stdlib slice
+  written entirely in OCaml syntax: List (length, rev, rev_append, map,
+  filter, fold_left/right, append, iter, mem, for_all, exists, hd, tl,
+  nth), Option (map, bind, value, get, is_none, is_some), Result (map,
+  bind, is_ok, is_error). Loaded once via `ocaml-load-stdlib!`, cached
+  in `ocaml-stdlib-env`; `ocaml-run` and `ocaml-run-program` layer user
+  code on top via `ocaml-base-env`. The fact that these are written in
+  OCaml (not SX) and parse + evaluate cleanly is a substrate-validation
+  win: every parser, eval, match, ref, and module path proven by a
+  single nontrivial Ocaml program. 248/248 (+23).
 - 2026-05-08 Phase 4 — functors + module aliases (+5 tests, 225 total).
   Parser: `module F (M) = struct DECLS end` → `(:functor-def NAME PARAMS
   DECLS)`. `module N = expr` (where expr isn't `struct`) → `(:module-alias