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45 lines
1.3 KiB
Agda
45 lines
1.3 KiB
Agda
module Luau.Type where
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open import FFI.Data.Maybe using (Maybe; just; nothing)
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data Type : Set where
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nil : Type
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_⇒_ : Type → Type → Type
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none : Type
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any : Type
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number : Type
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_∪_ : Type → Type → Type
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_∩_ : Type → Type → Type
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src : Type → Type
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src nil = none
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src (S ⇒ T) = S
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src none = none
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src any = any
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src number = none
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src (S ∪ T) = (src S) ∪ (src T)
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src (S ∩ T) = (src S) ∩ (src T)
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tgt : Type → Type
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tgt nil = none
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tgt (S ⇒ T) = T
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tgt none = none
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tgt any = any
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tgt number = none
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tgt (S ∪ T) = (tgt S) ∪ (tgt T)
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tgt (S ∩ T) = (tgt S) ∩ (tgt T)
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optional : Type → Type
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optional nil = nil
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optional (T ∪ nil) = (T ∪ nil)
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optional T = (T ∪ nil)
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normalizeOptional : Type → Type
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normalizeOptional (S ∪ T) with normalizeOptional S | normalizeOptional T
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normalizeOptional (S ∪ T) | (S′ ∪ nil) | (T′ ∪ nil) = (S′ ∪ T′) ∪ nil
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normalizeOptional (S ∪ T) | S′ | (T′ ∪ nil) = (S′ ∪ T′) ∪ nil
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normalizeOptional (S ∪ T) | (S′ ∪ nil) | T′ = (S′ ∪ T′) ∪ nil
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normalizeOptional (S ∪ T) | S′ | nil = optional S′
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normalizeOptional (S ∪ T) | nil | T′ = optional T′
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normalizeOptional (S ∪ T) | S′ | T′ = S′ ∪ T′
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normalizeOptional T = T
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