13 lines
372 B
Text
13 lines
372 B
Text
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--| Returns `True` if the `Optional` value is absent and `False` if present
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let null
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: ∀(a : Type) → Optional a → Bool
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= λ(a : Type) →
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λ(xs : Optional a) →
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merge { Some = λ(_ : a) → False, None = True } xs
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let example0 = assert : null Natural (Some 2) ≡ False
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let example1 = assert : null Natural (None Natural) ≡ True
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in null
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