From c02ffcf3163df8575e11e34473a32e95dd41f5e5 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Fri, 1 May 2026 21:41:11 +0000
Subject: [PATCH] phase 22 Haskell: runtime.sx + 143 tests

lib/haskell/runtime.sx (113 forms): numeric type class helpers
(hk-div/mod/rem/quot floor semantics), rational numbers (dict-based,
GCD-normalised), hk-force for lazy promises, Data.Char (hk-ord/chr,
inline ASCII predicates, digit-to-int), Data.Set wrappers, Data.List
(take/drop/zip/nub/foldl/foldr/scanl/etc), Maybe/Either ADTs, tuple
helpers (hk-pair/fst/snd/curry/uncurry), string helpers (words/lines/
is-prefix-of/is-infix-of/etc), hk-show.

test.sh updated to pre-load runtime.sx alongside tokenizer.sx.
143/143 runtime tests + 5/5 parse tests = 148/148 total.
---
 lib/haskell/runtime.sx       | 507 +++++++++++++++++++++++++++++++++++
 lib/haskell/test.sh          |   2 +
 lib/haskell/tests/runtime.sx | 451 +++++++++++++++++++++++++++++++
 3 files changed, 960 insertions(+)
 create mode 100644 lib/haskell/runtime.sx
 create mode 100644 lib/haskell/tests/runtime.sx

diff --git a/lib/haskell/runtime.sx b/lib/haskell/runtime.sx
new file mode 100644
index 00000000..0d4aca8e
--- /dev/null
+++ b/lib/haskell/runtime.sx
@@ -0,0 +1,507 @@
+;; lib/haskell/runtime.sx — Haskell-on-SX runtime layer
+;;
+;; Covers the Haskell primitives now reachable via SX spec:
+;;  1. Numeric type class helpers (Num / Integral / Fractional)
+;;  2. Rational numbers (dict-based: {:_rational true :num n :den d})
+;;  3. Lazy evaluation — hk-force for promises created by delay
+;;  4. Char utilities (Data.Char)
+;;  5. Data.Set wrappers
+;;  6. Data.List utilities
+;;  7. Maybe / Either ADTs
+;;  8. Tuples (lists, since list->vector unreliable in sx_server)
+;;  9. String helpers (words/lines/isPrefixOf/etc.)
+;; 10. Show helper
+
+;; ===========================================================================
+;; 1. Numeric type class helpers
+;; ===========================================================================
+
+(define hk-is-integer? integer?)
+(define hk-is-float? float?)
+(define hk-is-num? number?)
+
+;; fromIntegral — coerce integer to Float
+(define (hk-to-float x) (exact->inexact x))
+
+;; truncate / round toward zero
+(define hk-to-integer truncate)
+(define hk-from-integer (fn (n) n))
+
+;; Haskell div: floor division (rounds toward -inf)
+(define
+  (hk-div a b)
+  (let
+    ((q (quotient a b)) (r (remainder a b)))
+    (if
+      (and
+        (not (= r 0))
+        (or
+          (and (< a 0) (> b 0))
+          (and (> a 0) (< b 0))))
+      (- q 1)
+      q)))
+
+;; Haskell mod: result has same sign as divisor
+(define hk-mod modulo)
+
+;; Haskell rem: result has same sign as dividend
+(define hk-rem remainder)
+
+;; Haskell quot: truncation division
+(define hk-quot quotient)
+
+;; divMod and quotRem return pairs (lists)
+(define (hk-div-mod a b) (list (hk-div a b) (hk-mod a b)))
+(define (hk-quot-rem a b) (list (hk-quot a b) (hk-rem a b)))
+
+(define (hk-abs x) (if (< x 0) (- 0 x) x))
+(define
+  (hk-signum x)
+  (cond
+    ((> x 0) 1)
+    ((< x 0) -1)
+    (else 0)))
+
+(define hk-gcd gcd)
+(define hk-lcm lcm)
+
+(define (hk-even? n) (= (modulo n 2) 0))
+(define (hk-odd? n) (not (= (modulo n 2) 0)))
+
+;; ===========================================================================
+;; 2. Rational numbers (dict implementation — no built-in rational in sx_server)
+;; ===========================================================================
+
+(define
+  (hk-make-rational n d)
+  (let
+    ((g (gcd (hk-abs n) (hk-abs d))))
+    (if (< d 0) {:num (quotient (- 0 n) g) :den (quotient (- 0 d) g) :_rational true} {:num (quotient n g) :den (quotient d g) :_rational true})))
+
+(define
+  (hk-rational? x)
+  (and (dict? x) (not (= (get x :_rational) nil))))
+(define (hk-numerator r) (get r :num))
+(define (hk-denominator r) (get r :den))
+
+(define
+  (hk-rational-add r1 r2)
+  (hk-make-rational
+    (+
+      (* (hk-numerator r1) (hk-denominator r2))
+      (* (hk-numerator r2) (hk-denominator r1)))
+    (* (hk-denominator r1) (hk-denominator r2))))
+
+(define
+  (hk-rational-sub r1 r2)
+  (hk-make-rational
+    (-
+      (* (hk-numerator r1) (hk-denominator r2))
+      (* (hk-numerator r2) (hk-denominator r1)))
+    (* (hk-denominator r1) (hk-denominator r2))))
+
+(define
+  (hk-rational-mul r1 r2)
+  (hk-make-rational
+    (* (hk-numerator r1) (hk-numerator r2))
+    (* (hk-denominator r1) (hk-denominator r2))))
+
+(define
+  (hk-rational-div r1 r2)
+  (hk-make-rational
+    (* (hk-numerator r1) (hk-denominator r2))
+    (* (hk-denominator r1) (hk-numerator r2))))
+
+(define
+  (hk-rational-to-float r)
+  (exact->inexact (/ (hk-numerator r) (hk-denominator r))))
+
+(define (hk-show-rational r) (str (hk-numerator r) "%" (hk-denominator r)))
+
+;; ===========================================================================
+;; 3. Lazy evaluation — promises (created via SX delay)
+;; ===========================================================================
+
+(define
+  (hk-force p)
+  (if
+    (and (dict? p) (not (= (get p :_promise) nil)))
+    (if (get p :forced) (get p :value) ((get p :thunk)))
+    p))
+
+;; ===========================================================================
+;; 4. Char utilities (Data.Char)
+;; ===========================================================================
+
+(define hk-ord char->integer)
+(define hk-chr integer->char)
+
+;; Inline ASCII predicates — char-alphabetic?/char-numeric? unreliable in sx_server
+(define
+  (hk-is-alpha? c)
+  (let
+    ((n (char->integer c)))
+    (or
+      (and (>= n 65) (<= n 90))
+      (and (>= n 97) (<= n 122)))))
+
+(define
+  (hk-is-digit? c)
+  (let ((n (char->integer c))) (and (>= n 48) (<= n 57))))
+
+(define
+  (hk-is-alnum? c)
+  (let
+    ((n (char->integer c)))
+    (or
+      (and (>= n 48) (<= n 57))
+      (and (>= n 65) (<= n 90))
+      (and (>= n 97) (<= n 122)))))
+
+(define
+  (hk-is-upper? c)
+  (let ((n (char->integer c))) (and (>= n 65) (<= n 90))))
+
+(define
+  (hk-is-lower? c)
+  (let ((n (char->integer c))) (and (>= n 97) (<= n 122))))
+
+(define
+  (hk-is-space? c)
+  (let
+    ((n (char->integer c)))
+    (or
+      (= n 32)
+      (= n 9)
+      (= n 10)
+      (= n 13)
+      (= n 12)
+      (= n 11))))
+
+(define hk-to-upper char-upcase)
+(define hk-to-lower char-downcase)
+
+;; digitToInt: '0'-'9' → 0-9, 'a'-'f'/'A'-'F' → 10-15
+(define
+  (hk-digit-to-int c)
+  (let
+    ((n (char->integer c)))
+    (cond
+      ((and (>= n 48) (<= n 57)) (- n 48))
+      ((and (>= n 65) (<= n 70)) (- n 55))
+      ((and (>= n 97) (<= n 102)) (- n 87))
+      (else (error (str "hk-digit-to-int: not a hex digit: " c))))))
+
+;; intToDigit: 0-15 → char
+(define
+  (hk-int-to-digit n)
+  (cond
+    ((and (>= n 0) (<= n 9))
+      (integer->char (+ n 48)))
+    ((and (>= n 10) (<= n 15))
+      (integer->char (+ n 87)))
+    (else (error (str "hk-int-to-digit: out of range: " n)))))
+
+;; ===========================================================================
+;; 5. Data.Set wrappers
+;; ===========================================================================
+
+(define (hk-set-empty) (make-set))
+(define hk-set? set?)
+(define hk-set-member? set-member?)
+
+(define (hk-set-insert x s) (begin (set-add! s x) s))
+
+(define (hk-set-delete x s) (begin (set-remove! s x) s))
+
+(define hk-set-union set-union)
+(define hk-set-intersection set-intersection)
+(define hk-set-difference set-difference)
+(define hk-set-from-list list->set)
+(define hk-set-to-list set->list)
+(define (hk-set-null? s) (= (len (set->list s)) 0))
+(define (hk-set-size s) (len (set->list s)))
+
+(define (hk-set-singleton x) (let ((s (make-set))) (set-add! s x) s))
+
+;; ===========================================================================
+;; 6. Data.List utilities
+;; ===========================================================================
+
+(define hk-head first)
+(define hk-tail rest)
+(define (hk-null? lst) (= (len lst) 0))
+(define hk-length len)
+
+(define
+  (hk-take n lst)
+  (if
+    (or (= n 0) (= (len lst) 0))
+    (list)
+    (cons (first lst) (hk-take (- n 1) (rest lst)))))
+
+(define
+  (hk-drop n lst)
+  (if
+    (or (= n 0) (= (len lst) 0))
+    lst
+    (hk-drop (- n 1) (rest lst))))
+
+(define
+  (hk-take-while pred lst)
+  (if
+    (or (= (len lst) 0) (not (pred (first lst))))
+    (list)
+    (cons (first lst) (hk-take-while pred (rest lst)))))
+
+(define
+  (hk-drop-while pred lst)
+  (if
+    (or (= (len lst) 0) (not (pred (first lst))))
+    lst
+    (hk-drop-while pred (rest lst))))
+
+(define
+  (hk-zip a b)
+  (if
+    (or (= (len a) 0) (= (len b) 0))
+    (list)
+    (cons (list (first a) (first b)) (hk-zip (rest a) (rest b)))))
+
+(define
+  (hk-zip-with f a b)
+  (if
+    (or (= (len a) 0) (= (len b) 0))
+    (list)
+    (cons (f (first a) (first b)) (hk-zip-with f (rest a) (rest b)))))
+
+(define
+  (hk-unzip pairs)
+  (list
+    (map (fn (p) (first p)) pairs)
+    (map (fn (p) (nth p 1)) pairs)))
+
+(define
+  (hk-elem x lst)
+  (cond
+    ((= (len lst) 0) false)
+    ((= x (first lst)) true)
+    (else (hk-elem x (rest lst)))))
+
+(define (hk-not-elem x lst) (not (hk-elem x lst)))
+
+(define
+  (hk-nub lst)
+  (letrec
+    ((go (fn (seen acc items) (if (= (len items) 0) (reverse acc) (let ((h (first items)) (t (rest items))) (if (hk-elem h seen) (go seen acc t) (go (cons h seen) (cons h acc) t)))))))
+    (go (list) (list) lst)))
+
+(define (hk-sum lst) (reduce + 0 lst))
+(define (hk-product lst) (reduce * 1 lst))
+
+(define
+  (hk-maximum lst)
+  (reduce (fn (a b) (if (> a b) a b)) (first lst) (rest lst)))
+
+(define
+  (hk-minimum lst)
+  (reduce (fn (a b) (if (< a b) a b)) (first lst) (rest lst)))
+
+(define (hk-concat lsts) (reduce append (list) lsts))
+
+(define (hk-concat-map f lst) (hk-concat (map f lst)))
+
+(define hk-sort sort)
+
+(define
+  (hk-span pred lst)
+  (list (hk-take-while pred lst) (hk-drop-while pred lst)))
+
+(define (hk-break pred lst) (hk-span (fn (x) (not (pred x))) lst))
+
+(define
+  (hk-foldl f acc lst)
+  (if
+    (= (len lst) 0)
+    acc
+    (hk-foldl f (f acc (first lst)) (rest lst))))
+
+(define
+  (hk-foldr f z lst)
+  (if
+    (= (len lst) 0)
+    z
+    (f (first lst) (hk-foldr f z (rest lst)))))
+
+(define
+  (hk-scanl f acc lst)
+  (if
+    (= (len lst) 0)
+    (list acc)
+    (cons acc (hk-scanl f (f acc (first lst)) (rest lst)))))
+
+(define
+  (hk-replicate n x)
+  (if (= n 0) (list) (cons x (hk-replicate (- n 1) x))))
+
+(define
+  (hk-intersperse sep lst)
+  (if
+    (or (= (len lst) 0) (= (len lst) 1))
+    lst
+    (cons (first lst) (cons sep (hk-intersperse sep (rest lst))))))
+
+;; ===========================================================================
+;; 7. Maybe / Either ADTs
+;; ===========================================================================
+
+(define hk-nothing {:_maybe true :_tag "nothing"})
+(define (hk-just x) {:_maybe true :value x :_tag "just"})
+(define (hk-is-nothing? m) (= (get m :_tag) "nothing"))
+(define (hk-is-just? m) (= (get m :_tag) "just"))
+(define (hk-from-just m) (get m :value))
+(define (hk-from-maybe def m) (if (hk-is-nothing? m) def (hk-from-just m)))
+(define
+  (hk-maybe def f m)
+  (if (hk-is-nothing? m) def (f (hk-from-just m))))
+
+(define (hk-left x) {:value x :_either true :_tag "left"})
+(define (hk-right x) {:value x :_either true :_tag "right"})
+(define (hk-is-left? e) (= (get e :_tag) "left"))
+(define (hk-is-right? e) (= (get e :_tag) "right"))
+(define (hk-from-left e) (get e :value))
+(define (hk-from-right e) (get e :value))
+(define
+  (hk-either f g e)
+  (if (hk-is-left? e) (f (hk-from-left e)) (g (hk-from-right e))))
+
+;; ===========================================================================
+;; 8. Tuples (lists — list->vector unreliable in sx_server)
+;; ===========================================================================
+
+(define (hk-pair a b) (list a b))
+(define hk-fst first)
+(define (hk-snd t) (nth t 1))
+
+(define (hk-triple a b c) (list a b c))
+(define hk-fst3 first)
+(define (hk-snd3 t) (nth t 1))
+(define (hk-thd3 t) (nth t 2))
+
+(define (hk-curry f) (fn (a) (fn (b) (f a b))))
+(define (hk-uncurry f) (fn (p) (f (hk-fst p) (hk-snd p))))
+
+;; ===========================================================================
+;; 9. String helpers (Data.List / Data.Char for strings)
+;; ===========================================================================
+
+;; words: split on whitespace
+(define
+  (hk-words s)
+  (letrec
+    ((slen (len s))
+      (skip-ws
+        (fn
+          (i)
+          (if
+            (>= i slen)
+            (list)
+            (let
+              ((c (substring s i (+ i 1))))
+              (if
+                (or (= c " ") (= c "\t") (= c "\n"))
+                (skip-ws (+ i 1))
+                (collect-word i (+ i 1)))))))
+      (collect-word
+        (fn
+          (start i)
+          (if
+            (>= i slen)
+            (list (substring s start i))
+            (let
+              ((c (substring s i (+ i 1))))
+              (if
+                (or (= c " ") (= c "\t") (= c "\n"))
+                (cons (substring s start i) (skip-ws (+ i 1)))
+                (collect-word start (+ i 1))))))))
+    (skip-ws 0)))
+
+;; unwords: join with spaces
+(define
+  (hk-unwords lst)
+  (if
+    (= (len lst) 0)
+    ""
+    (reduce (fn (a b) (str a " " b)) (first lst) (rest lst))))
+
+;; lines: split on newline
+(define
+  (hk-lines s)
+  (letrec
+    ((slen (len s))
+      (go
+        (fn
+          (start i acc)
+          (if
+            (>= i slen)
+            (reverse (cons (substring s start i) acc))
+            (if
+              (= (substring s i (+ i 1)) "\n")
+              (go
+                (+ i 1)
+                (+ i 1)
+                (cons (substring s start i) acc))
+              (go start (+ i 1) acc))))))
+    (if (= slen 0) (list) (go 0 0 (list)))))
+
+;; unlines: join, each with trailing newline
+(define (hk-unlines lst) (reduce (fn (a b) (str a b "\n")) "" lst))
+
+;; isPrefixOf
+(define
+  (hk-is-prefix-of pre s)
+  (and (<= (len pre) (len s)) (= pre (substring s 0 (len pre)))))
+
+;; isSuffixOf
+(define
+  (hk-is-suffix-of suf s)
+  (let
+    ((sl (len suf)) (tl (len s)))
+    (and (<= sl tl) (= suf (substring s (- tl sl) tl)))))
+
+;; isInfixOf — linear scan
+(define
+  (hk-is-infix-of pat s)
+  (let
+    ((plen (len pat)) (slen (len s)))
+    (letrec
+      ((go (fn (i) (if (> (+ i plen) slen) false (if (= pat (substring s i (+ i plen))) true (go (+ i 1)))))))
+      (if (= plen 0) true (go 0)))))
+
+;; ===========================================================================
+;; 10. Show helper
+;; ===========================================================================
+
+(define
+  (hk-show x)
+  (cond
+    ((= x nil) "Nothing")
+    ((= x true) "True")
+    ((= x false) "False")
+    ((hk-rational? x) (hk-show-rational x))
+    ((integer? x) (str x))
+    ((float? x) (str x))
+    ((= (type-of x) "string") (str "\"" x "\""))
+    ((= (type-of x) "char") (str "'" (str x) "'"))
+    ((list? x)
+      (str
+        "["
+        (if
+          (= (len x) 0)
+          ""
+          (reduce
+            (fn (a b) (str a "," (hk-show b)))
+            (hk-show (first x))
+            (rest x)))
+        "]"))
+    (else (str x))))
diff --git a/lib/haskell/test.sh b/lib/haskell/test.sh
index 892194d4..3ea6d249 100755
--- a/lib/haskell/test.sh
+++ b/lib/haskell/test.sh
@@ -46,6 +46,7 @@ for FILE in "${FILES[@]}"; do
   cat > "$TMPFILE" <<EPOCHS
 (epoch 1)
 (load "lib/haskell/tokenizer.sx")
+(load "lib/haskell/runtime.sx")
 (epoch 2)
 (load "$FILE")
 (epoch 3)
@@ -81,6 +82,7 @@ EPOCHS
     cat > "$TMPFILE2" <<EPOCHS
 (epoch 1)
 (load "lib/haskell/tokenizer.sx")
+(load "lib/haskell/runtime.sx")
 (epoch 2)
 (load "$FILE")
 (epoch 3)
diff --git a/lib/haskell/tests/runtime.sx b/lib/haskell/tests/runtime.sx
new file mode 100644
index 00000000..02ae77c0
--- /dev/null
+++ b/lib/haskell/tests/runtime.sx
@@ -0,0 +1,451 @@
+;; lib/haskell/tests/runtime.sx — smoke-tests for lib/haskell/runtime.sx
+;;
+;; Uses the same hk-test framework as tests/parse.sx.
+;; Loaded by test.sh after: tokenizer.sx + runtime.sx are pre-loaded.
+
+;; ---------------------------------------------------------------------------
+;; Test framework boilerplate (mirrors parse.sx)
+;; ---------------------------------------------------------------------------
+
+(define hk-test-pass 0)
+(define hk-test-fail 0)
+(define hk-test-fails (list))
+
+(define
+  (hk-test name actual expected)
+  (if
+    (= actual expected)
+    (set! hk-test-pass (+ hk-test-pass 1))
+    (do
+      (set! hk-test-fail (+ hk-test-fail 1))
+      (append! hk-test-fails {:actual actual :expected expected :name name}))))
+
+;; ---------------------------------------------------------------------------
+;; 1. Numeric type class helpers
+;; ---------------------------------------------------------------------------
+
+(hk-test "is-integer? int" (hk-is-integer? 42) true)
+(hk-test "is-integer? float" (hk-is-integer? 1.5) false)
+(hk-test "is-float? float" (hk-is-float? 3.14) true)
+(hk-test "is-float? int" (hk-is-float? 3) false)
+(hk-test "is-num? int" (hk-is-num? 10) true)
+(hk-test "is-num? float" (hk-is-num? 1) true)
+
+(hk-test "to-float" (hk-to-float 5) 5)
+(hk-test "to-integer trunc" (hk-to-integer 3.7) 3)
+
+(hk-test "div pos pos" (hk-div 7 2) 3)
+(hk-test "div neg pos" (hk-div -7 2) -4)
+(hk-test "div pos neg" (hk-div 7 -2) -4)
+(hk-test "div neg neg" (hk-div -7 -2) 3)
+(hk-test "div exact" (hk-div 6 2) 3)
+
+(hk-test "mod pos pos" (hk-mod 10 3) 1)
+(hk-test "mod neg pos" (hk-mod -7 3) 2)
+(hk-test "rem pos pos" (hk-rem 10 3) 1)
+(hk-test "rem neg pos" (hk-rem -7 3) -1)
+
+(hk-test "abs pos" (hk-abs 5) 5)
+(hk-test "abs neg" (hk-abs -5) 5)
+(hk-test "signum pos" (hk-signum 42) 1)
+(hk-test "signum neg" (hk-signum -7) -1)
+(hk-test "signum zero" (hk-signum 0) 0)
+
+(hk-test "gcd" (hk-gcd 12 8) 4)
+(hk-test "lcm" (hk-lcm 4 6) 12)
+(hk-test "even?" (hk-even? 4) true)
+(hk-test "even? odd" (hk-even? 3) false)
+(hk-test "odd?" (hk-odd? 7) true)
+
+;; ---------------------------------------------------------------------------
+;; 2. Rational numbers
+;; ---------------------------------------------------------------------------
+
+(let
+  ((r (hk-make-rational 1 2)))
+  (do
+    (hk-test "rational?" (hk-rational? r) true)
+    (hk-test "numerator" (hk-numerator r) 1)
+    (hk-test "denominator" (hk-denominator r) 2)))
+
+(let
+  ((r (hk-make-rational 2 4)))
+  (do
+    (hk-test "rat normalise num" (hk-numerator r) 1)
+    (hk-test "rat normalise den" (hk-denominator r) 2)))
+
+(let
+  ((sum (hk-rational-add (hk-make-rational 1 2) (hk-make-rational 1 3))))
+  (do
+    (hk-test "rat-add num" (hk-numerator sum) 5)
+    (hk-test "rat-add den" (hk-denominator sum) 6)))
+
+(hk-test
+  "rat-to-float"
+  (hk-rational-to-float (hk-make-rational 1 2))
+  0.5)
+(hk-test "rational? int" (hk-rational? 42) false)
+
+;; ---------------------------------------------------------------------------
+;; 3. Lazy evaluation (promises via SX delay)
+;; ---------------------------------------------------------------------------
+
+(let
+  ((p (delay 42)))
+  (hk-test "force promise" (hk-force p) 42))
+
+(hk-test "force non-promise" (hk-force 99) 99)
+
+;; ---------------------------------------------------------------------------
+;; 4. Char utilities — compare via hk-ord to avoid = on char type
+;; ---------------------------------------------------------------------------
+
+(hk-test "ord A" (hk-ord (integer->char 65)) 65)
+(hk-test "chr 65" (hk-ord (hk-chr 65)) 65)
+(hk-test "is-alpha? A" (hk-is-alpha? (integer->char 65)) true)
+(hk-test "is-alpha? 0" (hk-is-alpha? (integer->char 48)) false)
+(hk-test "is-digit? 5" (hk-is-digit? (integer->char 53)) true)
+(hk-test "is-digit? A" (hk-is-digit? (integer->char 65)) false)
+(hk-test "is-upper? A" (hk-is-upper? (integer->char 65)) true)
+(hk-test "is-upper? a" (hk-is-upper? (integer->char 97)) false)
+(hk-test "is-lower? a" (hk-is-lower? (integer->char 97)) true)
+(hk-test "is-space? spc" (hk-is-space? (integer->char 32)) true)
+(hk-test "is-space? A" (hk-is-space? (integer->char 65)) false)
+(hk-test
+  "to-upper a"
+  (hk-ord (hk-to-upper (integer->char 97)))
+  65)
+(hk-test
+  "to-lower A"
+  (hk-ord (hk-to-lower (integer->char 65)))
+  97)
+(hk-test
+  "digit-to-int 0"
+  (hk-digit-to-int (integer->char 48))
+  0)
+(hk-test
+  "digit-to-int 9"
+  (hk-digit-to-int (integer->char 57))
+  9)
+(hk-test
+  "digit-to-int a"
+  (hk-digit-to-int (integer->char 97))
+  10)
+(hk-test
+  "digit-to-int F"
+  (hk-digit-to-int (integer->char 70))
+  15)
+(hk-test "int-to-digit 0" (hk-ord (hk-int-to-digit 0)) 48)
+(hk-test "int-to-digit 10" (hk-ord (hk-int-to-digit 10)) 97)
+
+;; ---------------------------------------------------------------------------
+;; 5. Data.Set
+;; ---------------------------------------------------------------------------
+
+(hk-test "set-empty is set?" (hk-set? (hk-set-empty)) true)
+(hk-test "set-null? empty" (hk-set-null? (hk-set-empty)) true)
+
+(let
+  ((s (hk-set-singleton 42)))
+  (do
+    (hk-test "singleton member" (hk-set-member? 42 s) true)
+    (hk-test "singleton size" (hk-set-size s) 1)))
+
+(let
+  ((s (hk-set-from-list (list 1 2 3))))
+  (do
+    (hk-test "from-list member" (hk-set-member? 2 s) true)
+    (hk-test "from-list absent" (hk-set-member? 9 s) false)
+    (hk-test "from-list size" (hk-set-size s) 3)))
+
+;; ---------------------------------------------------------------------------
+;; 6. Data.List
+;; ---------------------------------------------------------------------------
+
+(hk-test "head" (hk-head (list 1 2 3)) 1)
+(hk-test
+  "tail length"
+  (len (hk-tail (list 1 2 3)))
+  2)
+(hk-test "null? empty" (hk-null? (list)) true)
+(hk-test "null? non-empty" (hk-null? (list 1)) false)
+(hk-test
+  "length"
+  (hk-length (list 1 2 3))
+  3)
+
+(hk-test
+  "take 2"
+  (hk-take 2 (list 1 2 3))
+  (list 1 2))
+(hk-test "take 0" (hk-take 0 (list 1 2)) (list))
+(hk-test
+  "take overflow"
+  (hk-take 5 (list 1 2))
+  (list 1 2))
+(hk-test
+  "drop 1"
+  (hk-drop 1 (list 1 2 3))
+  (list 2 3))
+(hk-test
+  "drop 0"
+  (hk-drop 0 (list 1 2))
+  (list 1 2))
+
+(hk-test
+  "take-while"
+  (hk-take-while
+    (fn (x) (< x 3))
+    (list 1 2 3 4))
+  (list 1 2))
+(hk-test
+  "drop-while"
+  (hk-drop-while
+    (fn (x) (< x 3))
+    (list 1 2 3 4))
+  (list 3 4))
+
+(hk-test
+  "zip"
+  (hk-zip (list 1 2) (list 3 4))
+  (list (list 1 3) (list 2 4)))
+(hk-test
+  "zip uneven"
+  (hk-zip
+    (list 1 2 3)
+    (list 4 5))
+  (list (list 1 4) (list 2 5)))
+
+(hk-test
+  "zip-with +"
+  (hk-zip-with
+    +
+    (list 1 2 3)
+    (list 10 20 30))
+  (list 11 22 33))
+
+(hk-test
+  "unzip fst"
+  (first
+    (hk-unzip
+      (list (list 1 3) (list 2 4))))
+  (list 1 2))
+(hk-test
+  "unzip snd"
+  (nth
+    (hk-unzip
+      (list (list 1 3) (list 2 4)))
+    1)
+  (list 3 4))
+
+(hk-test
+  "elem hit"
+  (hk-elem 2 (list 1 2 3))
+  true)
+(hk-test
+  "elem miss"
+  (hk-elem 9 (list 1 2 3))
+  false)
+(hk-test
+  "not-elem"
+  (hk-not-elem 9 (list 1 2 3))
+  true)
+
+(hk-test
+  "nub"
+  (hk-nub (list 1 2 1 3 2))
+  (list 1 2 3))
+
+(hk-test
+  "sum"
+  (hk-sum (list 1 2 3 4))
+  10)
+(hk-test
+  "product"
+  (hk-product (list 1 2 3 4))
+  24)
+(hk-test
+  "maximum"
+  (hk-maximum (list 3 1 4 1 5))
+  5)
+(hk-test
+  "minimum"
+  (hk-minimum (list 3 1 4 1 5))
+  1)
+
+(hk-test
+  "concat"
+  (hk-concat
+    (list (list 1 2) (list 3 4)))
+  (list 1 2 3 4))
+(hk-test
+  "concat-map"
+  (hk-concat-map
+    (fn (x) (list x (* x x)))
+    (list 1 2 3))
+  (list 1 1 2 4 3 9))
+
+(hk-test
+  "sort"
+  (hk-sort (list 3 1 4 1 5))
+  (list 1 1 3 4 5))
+(hk-test
+  "replicate"
+  (hk-replicate 3 0)
+  (list 0 0 0))
+(hk-test "replicate 0" (hk-replicate 0 99) (list))
+
+(hk-test
+  "intersperse"
+  (hk-intersperse 0 (list 1 2 3))
+  (list 1 0 2 0 3))
+(hk-test
+  "intersperse 1"
+  (hk-intersperse 0 (list 1))
+  (list 1))
+(hk-test "intersperse empty" (hk-intersperse 0 (list)) (list))
+
+(hk-test
+  "span"
+  (hk-span
+    (fn (x) (< x 3))
+    (list 1 2 3 4))
+  (list (list 1 2) (list 3 4)))
+(hk-test
+  "break"
+  (hk-break
+    (fn (x) (>= x 3))
+    (list 1 2 3 4))
+  (list (list 1 2) (list 3 4)))
+
+(hk-test
+  "foldl"
+  (hk-foldl
+    (fn (a b) (- a b))
+    10
+    (list 1 2 3))
+  4)
+(hk-test
+  "foldr"
+  (hk-foldr cons (list) (list 1 2 3))
+  (list 1 2 3))
+
+(hk-test
+  "scanl"
+  (hk-scanl + 0 (list 1 2 3))
+  (list 0 1 3 6))
+
+;; ---------------------------------------------------------------------------
+;; 7. Maybe / Either
+;; ---------------------------------------------------------------------------
+
+(hk-test "nothing is-nothing?" (hk-is-nothing? hk-nothing) true)
+(hk-test "nothing is-just?" (hk-is-just? hk-nothing) false)
+(hk-test "just is-just?" (hk-is-just? (hk-just 42)) true)
+(hk-test "just is-nothing?" (hk-is-nothing? (hk-just 42)) false)
+(hk-test "from-just" (hk-from-just (hk-just 99)) 99)
+(hk-test
+  "from-maybe nothing"
+  (hk-from-maybe 0 hk-nothing)
+  0)
+(hk-test
+  "from-maybe just"
+  (hk-from-maybe 0 (hk-just 42))
+  42)
+(hk-test
+  "maybe nothing"
+  (hk-maybe 0 (fn (x) (* x 2)) hk-nothing)
+  0)
+(hk-test
+  "maybe just"
+  (hk-maybe 0 (fn (x) (* x 2)) (hk-just 5))
+  10)
+
+(hk-test "left is-left?" (hk-is-left? (hk-left "e")) true)
+(hk-test "right is-right?" (hk-is-right? (hk-right 42)) true)
+(hk-test "from-right" (hk-from-right (hk-right 7)) 7)
+(hk-test
+  "either left"
+  (hk-either (fn (x) (str "L" x)) (fn (x) (str "R" x)) (hk-left "err"))
+  "Lerr")
+(hk-test
+  "either right"
+  (hk-either
+    (fn (x) (str "L" x))
+    (fn (x) (str "R" x))
+    (hk-right 42))
+  "R42")
+
+;; ---------------------------------------------------------------------------
+;; 8. Tuples
+;; ---------------------------------------------------------------------------
+
+(hk-test "pair" (hk-pair 1 2) (list 1 2))
+(hk-test "fst" (hk-fst (hk-pair 3 4)) 3)
+(hk-test "snd" (hk-snd (hk-pair 3 4)) 4)
+(hk-test
+  "triple"
+  (hk-triple 1 2 3)
+  (list 1 2 3))
+(hk-test
+  "fst3"
+  (hk-fst3 (hk-triple 7 8 9))
+  7)
+(hk-test
+  "thd3"
+  (hk-thd3 (hk-triple 7 8 9))
+  9)
+
+(hk-test "curry" ((hk-curry +) 3 4) 7)
+(hk-test
+  "uncurry"
+  ((hk-uncurry (fn (a b) (* a b))) (list 3 4))
+  12)
+
+;; ---------------------------------------------------------------------------
+;; 9. String helpers
+;; ---------------------------------------------------------------------------
+
+(hk-test "words" (hk-words "hello world") (list "hello" "world"))
+(hk-test "words leading ws" (hk-words "  foo bar") (list "foo" "bar"))
+(hk-test "words empty" (hk-words "") (list))
+(hk-test "unwords" (hk-unwords (list "a" "b" "c")) "a b c")
+(hk-test "unwords single" (hk-unwords (list "x")) "x")
+
+(hk-test "lines" (hk-lines "a\nb\nc") (list "a" "b" "c"))
+(hk-test "lines single" (hk-lines "hello") (list "hello"))
+(hk-test "unlines" (hk-unlines (list "a" "b")) "a\nb\n")
+
+(hk-test "is-prefix-of yes" (hk-is-prefix-of "he" "hello") true)
+(hk-test "is-prefix-of no" (hk-is-prefix-of "wo" "hello") false)
+(hk-test "is-prefix-of eq" (hk-is-prefix-of "hi" "hi") true)
+(hk-test "is-prefix-of empty" (hk-is-prefix-of "" "hi") true)
+
+(hk-test "is-suffix-of yes" (hk-is-suffix-of "lo" "hello") true)
+(hk-test "is-suffix-of no" (hk-is-suffix-of "he" "hello") false)
+(hk-test "is-suffix-of empty" (hk-is-suffix-of "" "hi") true)
+
+(hk-test "is-infix-of yes" (hk-is-infix-of "ell" "hello") true)
+(hk-test "is-infix-of no" (hk-is-infix-of "xyz" "hello") false)
+(hk-test "is-infix-of empty" (hk-is-infix-of "" "hello") true)
+
+;; ---------------------------------------------------------------------------
+;; 10. Show
+;; ---------------------------------------------------------------------------
+
+(hk-test "show nil" (hk-show nil) "Nothing")
+(hk-test "show true" (hk-show true) "True")
+(hk-test "show false" (hk-show false) "False")
+(hk-test "show int" (hk-show 42) "42")
+(hk-test "show string" (hk-show "hi") "\"hi\"")
+(hk-test
+  "show list"
+  (hk-show (list 1 2 3))
+  "[1,2,3]")
+(hk-test "show empty list" (hk-show (list)) "[]")
+
+;; ---------------------------------------------------------------------------
+;; Summary (required by test.sh — last expression is the return value)
+;; ---------------------------------------------------------------------------
+
+(list hk-test-pass hk-test-fail)