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39 lines
839 B
Idris
39 lines
839 B
Idris
%default total
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-- We put it all in a failing block so as not to pollute the scope
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-- The point is that because we have not specified `[search a]` when
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-- defining `Wrap` then we cannot find the `Wrap` implementation in
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-- the test.
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failing "Can't find an implementation for Wrap ?ph Nat."
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record Wrap (phantom : Type) (a : Type) where
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constructor MkWrap
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unWrap : a
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%hint
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zero : Wrap Bool Nat
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zero = MkWrap 0
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getWrappedVal : Wrap ph a => a
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getWrappedVal @{w} = unWrap w
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test : Main.getWrappedVal === Z
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test = Refl
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record Wrap (phantom : Type) (a : Type) where
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-- whereas this will give us the right behaviour
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[search a]
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constructor MkWrap
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unWrap : a
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%hint
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zero : Wrap Bool Nat
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zero = MkWrap 0
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getWrappedVal : Wrap ph a => a
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getWrappedVal @{w} = unWrap w
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test : Main.getWrappedVal === Z
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test = Refl
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