Origin of The Terms
The origin of these terms is in category theory, where the types in the type system form a category C, in which morphisms represent the subtype relationship.
Defining a function that accepts type p and returns type r creates a new type p → r in the type system; the new function name is associated with that type. This function definition operator is actually a functor F : C × C → C that creates the said type. From the substitution principle above, this functor must be contravariant in the first argument and covariant in the second.
Read more about this topic: Covariance And Contravariance (computer Science)
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“In the woods in a winter afternoon one will see as readily the origin of the stained glass window, with which Gothic cathedrals are adorned, in the colors of the western sky seen through the bare and crossing branches of the forest.”
—Ralph Waldo Emerson (1803–1882)
“In the woods in a winter afternoon one will see as readily the origin of the stained glass window, with which Gothic cathedrals are adorned, in the colors of the western sky seen through the bare and crossing branches of the forest.”
—Ralph Waldo Emerson (1803–1882)
“The essence of morality is a questioning about morality; and the decisive move of human life is to use ceaselessly all light to look for the origin of the opposition between good and evil.”
—Georges Bataille (1897–1962)
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—Joan Didion (b. 1934)