mk: phase 3 — run* / run / reify, 18 new tests

run.sx: reify-name builds canonical "_.N" symbols; reify-s walks a term
left-to-right and assigns each unbound var its index in the discovery
order; reify combines the two with two walk* passes. run-n is the
runtime defmacro: binds the query var, takes ≤ n stream answers, reifies
each. run* and run are sugar around it.

First classic miniKanren tests green:
  (run* q (== q 1))                              → (1)
  (run* q (conde ((== q 1)) ((== q 2))))         → (1 2)
  (run* q (fresh (x y) (== q (list x y))))       → ((_.0 _.1))

128/128 cumulative.

lib/minikanren/tests/run.sx

@@ -0,0 +1,114 @@
+;; lib/minikanren/tests/run.sx — Phase 3 tests for run* / run / reify.
+
+;; --- canonical TRS one-liners ---
+
+(mk-test "run*-eq-one" (run* q (== q 1)) (list 1))
+(mk-test "run*-eq-string" (run* q (== q "hello")) (list "hello"))
+(mk-test "run*-eq-symbol" (run* q (== q (quote sym))) (list (quote sym)))
+(mk-test "run*-fail-empty" (run* q (== 1 2)) (list))
+
+;; --- run with a count ---
+
+(mk-test
+  "run-3-of-many"
+  (run
+    3
+    q
+    (conde
+      ((== q 1))
+      ((== q 2))
+      ((== q 3))
+      ((== q 4))
+      ((== q 5))))
+  (list 1 2 3))
+
+(mk-test "run-zero-empty" (run 0 q (== q 1)) (list))
+
+(mk-test
+  "run-1-takes-one"
+  (run 1 q (conde ((== q "a")) ((== q "b"))))
+  (list "a"))
+
+;; --- reification: unbound vars get _.N left-to-right ---
+
+(mk-test
+  "reify-single-unbound"
+  (run* q (fresh (x) (== q x)))
+  (list (make-symbol "_.0")))
+
+(mk-test
+  "reify-pair-unbound"
+  (run* q (fresh (x y) (== q (list x y))))
+  (list (list (make-symbol "_.0") (make-symbol "_.1"))))
+
+(mk-test
+  "reify-mixed-bound-unbound"
+  (run* q (fresh (x y) (== q (list 1 x 2 y))))
+  (list
+    (list 1 (make-symbol "_.0") 2 (make-symbol "_.1"))))
+
+(mk-test
+  "reify-shared-unbound-same-name"
+  (run* q (fresh (x) (== q (list x x))))
+  (list (list (make-symbol "_.0") (make-symbol "_.0"))))
+
+(mk-test
+  "reify-distinct-unbound-distinct-names"
+  (run* q (fresh (x y) (== q (list x y x y))))
+  (list
+    (list
+      (make-symbol "_.0")
+      (make-symbol "_.1")
+      (make-symbol "_.0")
+      (make-symbol "_.1"))))
+
+;; --- conde + run* ---
+
+(mk-test
+  "run*-conde-three"
+  (run*
+    q
+    (conde ((== q 1)) ((== q 2)) ((== q 3))))
+  (list 1 2 3))
+
+(mk-test
+  "run*-conde-fresh-mix"
+  (run*
+    q
+    (conde ((fresh (x) (== q (list 1 x)))) ((== q "ground"))))
+  (list (list 1 (make-symbol "_.0")) "ground"))
+
+;; --- run* + conjunction ---
+
+(mk-test
+  "run*-conj-binds-q"
+  (run* q (fresh (x) (== x 5) (== q (list x x))))
+  (list (list 5 5)))
+
+;; --- run* + condu ---
+
+(mk-test
+  "run*-condu-first-wins"
+  (run* q (condu ((== q 1)) ((== q 2))))
+  (list 1))
+
+(mk-test
+  "run*-onceo-trim"
+  (run* q (onceo (conde ((== q "a")) ((== q "b")))))
+  (list "a"))
+
+;; --- multi-goal run ---
+
+(mk-test
+  "run*-three-goals"
+  (run*
+    q
+    (fresh
+      (x y z)
+      (== x 1)
+      (== y 2)
+      (== z 3)
+      (== q (list x y z))))
+  (list (list 1 2 3)))
+
+(mk-tests-run!)