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Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
87 lines
2.8 KiB
Plaintext
87 lines
2.8 KiB
Plaintext
;; class-defaults.sx — Phase 13: class default method implementations.
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;; ── Eq default: myNeq derived from myEq via `not (myEq x y)` ──
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(define
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hk-myeq-source
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"class MyEq a where\n myEq :: a -> a -> Bool\n myNeq :: a -> a -> Bool\n myNeq x y = not (myEq x y)\ninstance MyEq Int where\n myEq x y = x == y\n")
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(hk-test
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"Eq default: myNeq 3 5 = True (no explicit myNeq in instance)"
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(hk-deep-force (hk-run (str hk-myeq-source "main = myNeq 3 5\n")))
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(list "True"))
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(hk-test
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"Eq default: myNeq 3 3 = False"
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(hk-deep-force (hk-run (str hk-myeq-source "main = myNeq 3 3\n")))
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(list "False"))
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(hk-test
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"Eq default: myEq still works in same instance"
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(hk-deep-force (hk-run (str hk-myeq-source "main = myEq 7 7\n")))
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(list "True"))
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;; ── Override path: instance can still provide the method explicitly. ──
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(hk-test
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"Default override: instance-provided beats class default"
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(hk-deep-force
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(hk-run
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"class Hi a where\n greet :: a -> String\n greet x = \"default\"\ninstance Hi Bool where\n greet x = \"override\"\nmain = greet True"))
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"override")
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(hk-test
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"Default fallback: empty instance picks default"
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(hk-deep-force
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(hk-run
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"class Hi a where\n greet :: a -> String\n greet x = \"default\"\ninstance Hi Bool where\nmain = greet True"))
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"default")
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(define
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hk-myord-source
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"class MyOrd a where\n myCmp :: a -> a -> Bool\n myMax :: a -> a -> a\n myMin :: a -> a -> a\n myMax a b = if myCmp a b then a else b\n myMin a b = if myCmp a b then b else a\ninstance MyOrd Int where\n myCmp x y = x >= y\n")
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(hk-test
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"Ord default: myMax 3 5 = 5"
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(hk-deep-force (hk-run (str hk-myord-source "main = myMax 3 5\n")))
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5)
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(hk-test
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"Ord default: myMax 8 2 = 8"
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(hk-deep-force (hk-run (str hk-myord-source "main = myMax 8 2\n")))
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8)
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(hk-test
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"Ord default: myMin 3 5 = 3"
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(hk-deep-force (hk-run (str hk-myord-source "main = myMin 3 5\n")))
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3)
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(hk-test
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"Ord default: myMin 8 2 = 2"
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(hk-deep-force (hk-run (str hk-myord-source "main = myMin 8 2\n")))
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2)
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(hk-test
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"Ord default: myMax of equals returns first"
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(hk-deep-force (hk-run (str hk-myord-source "main = myMax 4 4\n")))
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4)
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(define
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hk-mynum-source
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"class MyNum a where\n mySub :: a -> a -> a\n myLt :: a -> a -> Bool\n myNegate :: a -> a\n myAbs :: a -> a\n myNegate x = mySub (mySub x x) x\n myAbs x = if myLt x (mySub x x) then myNegate x else x\ninstance MyNum Int where\n mySub x y = x - y\n myLt x y = x < y\n")
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(hk-test
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"Num default: myNegate 5 = -5"
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(hk-deep-force (hk-run (str hk-mynum-source "main = myNegate 5\n")))
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-5)
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(hk-test
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"Num default: myAbs (myNegate 7) = 7"
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(hk-deep-force (hk-run (str hk-mynum-source "main = myAbs (myNegate 7)\n")))
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7)
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(hk-test
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"Num default: myAbs 9 = 9"
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(hk-deep-force (hk-run (str hk-mynum-source "main = myAbs 9\n")))
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9)
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{:fails hk-test-fails :pass hk-test-pass :fail hk-test-fail}
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