Parametric polymorphism: Difference between revisions

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 If we have a tree of integers, i.e. <var>f</var> is <code>Tree</code> and <var>a</var> is <code>Integer</code>, then the type of <code>add1Everywhere</code> is <code>Tree Integer -> Tree Integer</code>.
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+=={{header|Inform 7}}==
+Phrases (the equivalent of global functions) can be defined with type parameters:
+<lang inform7>Polymorphism is a room.
+To find (V - K) in (L - list of values of kind K):
+	repeat with N running from 1 to the number of entries in L:
+		if entry N in L is V:
+			say "Found [V] at entry [N] in [L].";
+			stop;
+	say "Did not find [V] in [L]."
+When play begins:
+	find "needle" in {"parrot", "needle", "rutabaga"};
+	find 6 in {2, 3, 4};
+	end the story.</lang>
+Inform 7 does not allow user-defined parametric types. Some built-in types can be parameterized, though:
+<lang inform7>list of numbers
+relation of texts to rooms
+object based rulebook producing a number
+description of things
+activity on things
+number valued property
+text valued table column
+phrase (text, text) -> number</lang>
 =={{header|Java}}==