Data commit

Task/Constrained-genericity/Haskell/constrained-genericity-1.hs

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+class Eatable a where
+  eat :: a -> String

Task/Constrained-genericity/Haskell/constrained-genericity-2.hs

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+data (Eatable a) => FoodBox a = F [a]

Task/Constrained-genericity/Haskell/constrained-genericity-3.hs

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+data Banana = Foo -- the implementation doesn't really matter in this case
+instance Eatable Banana where
+  eat _ = "I'm eating a banana"

Task/Constrained-genericity/Haskell/constrained-genericity-4.hs

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+instance Eatable Double where
+  eat d = "I'm eating " ++ show d

Task/Constrained-genericity/Haskell/constrained-genericity-5.hs

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+class Food a where
+  munch :: a -> String

Task/Constrained-genericity/Haskell/constrained-genericity-6.hs

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+instance (Food a) => Eatable a where
+  eat x = munch x

Task/Constrained-genericity/Haskell/constrained-genericity-7.hs

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+import Utils        # From the UniLib package to get the Class class.
+
+class Eatable:Class()
+end
+
+class Fish:Eatable(name)
+    method eat(); write("Eating "+name); end
+end
+
+class Rock:Class(name)
+    method eat(); write("Eating "+name); end
+end
+
+class FoodBox(A)
+initially
+    every item := !A do if "Eatable" == item.Type() then next else bad := "yes"
+    return /bad
+end
+
+procedure main()
+    if FoodBox([Fish("salmon")]) then write("Edible") else write("Inedible")
+    if FoodBox([Rock("granite")]) then write("Edible") else write("Inedible")
+end