haskell: Phase 7 conformance — caesar.hs (+8 tests, 8/8)

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

lib/haskell/conformance.sh

@@ -20,7 +20,7 @@ if [ ! -x "$SX_SERVER" ]; then
   fi
 fi
 
-PROGRAMS=(fib sieve quicksort nqueens calculator collatz palindrome maybe fizzbuzz anagram roman binary either primes zipwith matrix wordcount powers)
+PROGRAMS=(fib sieve quicksort nqueens calculator collatz palindrome maybe fizzbuzz anagram roman binary either primes zipwith matrix wordcount powers caesar)
 PASS_COUNTS=()
 FAIL_COUNTS=()
 

lib/haskell/tests/program-caesar.sx

@@ -0,0 +1,80 @@
+;; caesar.hs — Caesar cipher.
+;; Source: https://rosettacode.org/wiki/Caesar_cipher#Haskell (adapted).
+;;
+;; Exercises chr, ord, isUpper, isLower, mod, string pattern matching
+;; (x:xs) over a String (which is now a [Char] string view), and map
+;; from the Phase 7 string=[Char] foundation.
+
+(define
+  hk-prog-val
+  (fn
+    (src name)
+    (hk-deep-force (get (hk-eval-program (hk-core src)) name))))
+
+(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))))
+
+(define
+  hk-caesar-source
+  "shift n c = if isUpper c\n              then chr (mod ((ord c) - 65 + n) 26 + 65)\n              else if isLower c\n                     then chr (mod ((ord c) - 97 + n) 26 + 97)\n                     else chr c\n\ncaesarRec n []     = []\ncaesarRec n (x:xs) = shift n x : caesarRec n xs\n\ncaesarMap n s = map (shift n) s\n")
+
+(hk-test
+  "caesar.hs — caesarRec 3 \"ABC\" = DEF"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 3 \"ABC\"\n") "r"))
+  (list "D" "E" "F"))
+
+(hk-test
+  "caesar.hs — caesarRec 13 \"Hello\" = Uryyb"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 13 \"Hello\"\n") "r"))
+  (list "U" "r" "y" "y" "b"))
+
+(hk-test
+  "caesar.hs — caesarRec 1 \"AZ\" wraps to BA"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 1 \"AZ\"\n") "r"))
+  (list "B" "A"))
+
+(hk-test
+  "caesar.hs — caesarRec 0 \"World\" identity"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 0 \"World\"\n") "r"))
+  (list "W" "o" "r" "l" "d"))
+
+(hk-test
+  "caesar.hs — caesarRec preserves punctuation"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 3 \"Hi!\"\n") "r"))
+  (list "K" "l" "!"))
+
+(hk-test
+  "caesar.hs — caesarMap 3 \"abc\" via map"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarMap 3 \"abc\"\n") "r"))
+  (list "d" "e" "f"))
+
+(hk-test
+  "caesar.hs — caesarMap 13 round-trips with caesarMap 13"
+  (hk-as-list
+    (hk-prog-val
+      (str
+        hk-caesar-source
+        "r = caesarMap 13 (foldr (\\c acc -> c : acc) [] (caesarMap 13 \"Hello\"))\n")
+      "r"))
+  (list "H" "e" "l" "l" "o"))
+
+(hk-test
+  "caesar.hs — caesarRec 25 \"AB\" = ZA"
+  (hk-as-list
+    (hk-prog-val (str hk-caesar-source "r = caesarRec 25 \"AB\"\n") "r"))
+  (list "Z" "A"))
+
+{:fails hk-test-fails :pass hk-test-pass :fail hk-test-fail}

plans/haskell-completeness.md

@@ -284,6 +284,15 @@ No OCaml changes are needed. The view type is fully representable as an SX dict.
 
 _Newest first._
 
+**2026-05-06** — Phase 7 conformance (caesar.hs):
+- New `lib/haskell/tests/program-caesar.sx` (8 tests). Caesar cipher exercising
+  `chr`, `ord`, `isUpper`, `isLower`, `mod`, `map`, and `(x:xs)` pattern matching
+  over native String values via the Phase 7 string-view path. Adapted from
+  https://rosettacode.org/wiki/Caesar_cipher#Haskell.
+- `caesar` added to `PROGRAMS` in `lib/haskell/conformance.sh`. Suite isolated:
+  8/8 passing. Note: `else chr c` in `shift` keeps the char-as-string output type
+  consistent with the alpha branches (pattern bind on a string view yields an int).
+
 **2026-05-06** — Phase 7 complete (string-view O(1) head/tail + `++` native concat):
 - `runtime.sx`: added `hk-str?`, `hk-str-head`, `hk-str-tail`, `hk-str-null?`.
   String views are `{:hk-str buf :hk-off n}` dicts; native SX strings satisfy the