haskell: Phase 10 — fromIntegral verified as prelude identity (+4 tests, 14/14)

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

lib/haskell/tests/numerics.sx

@@ -13,6 +13,16 @@
 ;; we don't yet support arbitrary-precision Integer. Documented; unbounded
 ;; Integer is out of scope for Phase 10 — see Phase 11+ if it becomes needed.
 
+(define
+  hk-as-list
+  (fn
+    (xs)
+    (cond
+      ((and (list? xs) (= (first xs) "[]")) (list))
+      ((and (list? xs) (= (first xs) ":"))
+        (cons (nth xs 1) (hk-as-list (nth xs 2))))
+      (:else xs))))
+
 (hk-test
   "factorial 10 = 3628800 (small, exact)"
   (hk-deep-force
@@ -68,4 +78,24 @@
   (hk-deep-force (hk-run "main = div 1000000000000000000 1000000000"))
   1000000000)
 
+(hk-test
+  "fromIntegral 42 = 42 (identity in our runtime)"
+  (hk-deep-force (hk-run "main = fromIntegral 42"))
+  42)
+
+(hk-test
+  "fromIntegral preserves negative"
+  (hk-deep-force (hk-run "main = fromIntegral (negate 7)"))
+  -7)
+
+(hk-test
+  "fromIntegral round-trips through arithmetic"
+  (hk-deep-force (hk-run "main = fromIntegral 5 + fromIntegral 3"))
+  8)
+
+(hk-test
+  "fromIntegral in a program (mixing with map)"
+  (hk-as-list (hk-deep-force (hk-run "main = map fromIntegral [1,2,3]")))
+  (list 1 2 3))
+
 {:fails hk-test-fails :pass hk-test-pass :fail hk-test-fail}