spec: multiple values — values/call-with-values/let-values/define-values

25 tests pass on both JS and OCaml hosts. Uses dict marker
{:_values true :_list [...]} for 0/2+ values; 1 value passes
through directly. step-sf-define extended to desugar shorthand
(define (name params) body) forms on both hosts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

spec/tests/test-values.sx

@@ -0,0 +1,172 @@
+(defsuite
+  "multiple-values"
+  (deftest
+    "values single returns value directly"
+    (do
+      (assert= 42 (values 42))
+      (assert= "hi" (values "hi"))
+      (assert= nil (values nil))))
+  (deftest
+    "values multiple returns marker dict"
+    (do
+      (let
+        ((v (values 1 2 3)))
+        (assert (dict? v))
+        (assert= true (get v :_values false))
+        (assert-equal (list 1 2 3) (get v :_list)))))
+  (deftest
+    "call-with-values basic two values"
+    (do
+      (assert=
+        3
+        (call-with-values
+          (fn () (values 1 2))
+          (fn (a b) (+ a b))))))
+  (deftest
+    "call-with-values three values"
+    (do
+      (assert=
+        6
+        (call-with-values
+          (fn () (values 1 2 3))
+          (fn (a b c) (+ a b c))))))
+  (deftest
+    "call-with-values single value passthrough"
+    (do
+      (assert= 10 (call-with-values (fn () 10) (fn (x) x)))))
+  (deftest
+    "call-with-values passes non-values result as single arg"
+    (do (assert= "hello" (call-with-values (fn () "hello") (fn (x) x)))))
+  (deftest
+    "call-with-values with string concat"
+    (do
+      (assert=
+        "ab"
+        (call-with-values (fn () (values "a" "b")) (fn (a b) (str a b))))))
+  (deftest
+    "let-values basic two bindings"
+    (do
+      (let-values
+        (((a b) (values 10 20)))
+        (assert= 10 a)
+        (assert= 20 b))))
+  (deftest
+    "let-values computes with bindings"
+    (do
+      (let-values
+        (((x y) (values 3 4)))
+        (assert= 7 (+ x y)))))
+  (deftest
+    "let-values three values"
+    (do
+      (let-values
+        (((a b c) (values 1 2 3)))
+        (assert= 6 (+ a b c)))))
+  (deftest
+    "let-values single value binding"
+    (do (let-values (((x) (values 42))) (assert= 42 x))))
+  (deftest
+    "let-values multiple binding clauses"
+    (do
+      (let-values
+        (((a b) (values 1 2))
+          ((c d) (values 3 4)))
+        (assert= 10 (+ a b c d)))))
+  (deftest
+    "let-values body is multiple expressions"
+    (do
+      (let-values
+        (((a b) (values 5 6)))
+        (define sum (+ a b))
+        (assert= 11 sum))))
+  (deftest
+    "let-values with no bindings evals body"
+    (do (let-values () (assert= 99 99))))
+  (deftest
+    "define-values binds multiple names"
+    (do
+      (define-values (x y) (values 7 8))
+      (assert= 7 x)
+      (assert= 8 y)))
+  (deftest
+    "define-values three names"
+    (do
+      (define-values (a b c) (values 10 20 30))
+      (assert= 10 a)
+      (assert= 20 b)
+      (assert= 30 c)))
+  (deftest
+    "define-values single name"
+    (do (define-values (n) (values 42)) (assert= 42 n)))
+  (deftest
+    "define-values used in computation"
+    (do
+      (define-values (w h) (values 6 7))
+      (assert= 42 (* w h))))
+  (deftest
+    "values in let binding"
+    (do
+      (let
+        ((v (values 100 200)))
+        (assert= true (get v :_values false))
+        (assert= 100 (first (get v :_list))))))
+  (deftest
+    "call-with-values with swap"
+    (do
+      (define (swap a b) (values b a))
+      (assert=
+        5
+        (call-with-values
+          (fn () (swap 3 5))
+          (fn (first-val second-val) first-val)))))
+  (deftest
+    "let-values from function returning values"
+    (do
+      (define (min-max a b) (values (min a b) (max a b)))
+      (let-values
+        (((lo hi) (min-max 7 3)))
+        (assert= 3 lo)
+        (assert= 7 hi))))
+  (deftest
+    "nested let-values"
+    (do
+      (let-values
+        (((a b) (values 1 2)))
+        (let-values
+          (((c d) (values 3 4)))
+          (assert= 10 (+ a b c d))))))
+  (deftest
+    "call-with-values chained"
+    (do
+      (define
+        result
+        (call-with-values
+          (fn
+            ()
+            (call-with-values
+              (fn () (values 4 6))
+              (fn (a b) (* a b))))
+          (fn (x) x)))
+      (assert= 24 result)))
+  (deftest
+    "values zero args produces dict"
+    (do
+      (let
+        ((v (values)))
+        (assert (dict? v))
+        (assert (get v :_values false))
+        (assert-equal (list) (get v :_list)))))
+  (deftest
+    "let-values strings"
+    (do
+      (let-values
+        (((first-name last-name) (values "Alice" "Smith")))
+        (assert= "Alice Smith" (str first-name " " last-name)))))
+  (deftest
+    "define-values with list values"
+    (do
+      (define-values
+        (head tail)
+        (values 1 (list 2 3 4)))
+      (assert= 1 head)
+      (assert-equal (list 2 3 4) tail))))