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23 lines
689 B
Plaintext
23 lines
689 B
Plaintext
(doc Phantom "is a type without inhabitants and a free type variable, which is
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a fancy way of saying that it has no runtime representation.
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When trying to mark types programmatically using something like `the` but
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without the need for a special form, `Phantom` comes in handy.
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Example:
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```
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(defn test [a]
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(Phantom.ensure a (the (Phantom Int) (Phantom.init))))
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(println* (test 123l)) ; this will not compile
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```")
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(deftype (Phantom a) [])
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(defmodule Phantom
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(doc ensure "is a function that takes anything and a `Phantom`, ensuring that
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the type contained by the `Phantom` and the type of the first parameter match.")
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(sig ensure (Fn [a (Phantom a)] a))
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(defn ensure [a p] a)
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)
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