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rose-ash/lib/haskell/tests/program-shapes.sx
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haskell: Phase 13 conformance — shapes.hs (5/5), Phase 13 complete
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-07 14:38:07 +00:00

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;; shapes.hs — class Area with a default perimeter, two instances
;; using where-local helpers.
;;
;; Exercises Phase 13: class default method (perimeter), instance
;; methods that use `where`-bindings.
(define
hk-shapes-source
"class Shape a where\n area :: a -> Int\n perimeter :: a -> Int\n perimeter x = quadrilateral x\n where quadrilateral y = 2 * (sideA y + sideB y)\n sideA z = 1\n sideB z = 1\n\ndata Square = Square Int\ndata Rect = Rect Int Int\n\ninstance Shape Square where\n area (Square s) = s * s\n perimeter (Square s) = 4 * s\n\ninstance Shape Rect where\n area (Rect w h) = w * h\n perimeter (Rect w h) = peri\n where peri = 2 * (w + h)\n")
(hk-test
"shapes.hs — area of Square 5 = 25"
(hk-deep-force (hk-run (str hk-shapes-source "main = area (Square 5)\n")))
25)
(hk-test
"shapes.hs — perimeter of Square 5 = 20"
(hk-deep-force
(hk-run (str hk-shapes-source "main = perimeter (Square 5)\n")))
20)
(hk-test
"shapes.hs — area of Rect 3 4 = 12"
(hk-deep-force (hk-run (str hk-shapes-source "main = area (Rect 3 4)\n")))
12)
(hk-test
"shapes.hs — perimeter of Rect 3 4 = 14 (via where-bound)"
(hk-deep-force
(hk-run (str hk-shapes-source "main = perimeter (Rect 3 4)\n")))
14)
(hk-test
"shapes.hs — Square sums area + perimeter"
(hk-deep-force
(hk-run
(str hk-shapes-source "main = area (Square 4) + perimeter (Square 4)\n")))
32)
{:fails hk-test-fails :pass hk-test-pass :fail hk-test-fail}