64 lines
1.3 KiB
Idris
64 lines
1.3 KiB
Idris
module Data.Tensor
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%default total
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public export
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record Isomorphism a b where
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constructor MkIso
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fwd : a -> b
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bwd : b -> a
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public export
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interface Bifunctor ten => Associative ten where
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assoc : Isomorphism (a `ten` (b `ten` c)) ((a `ten` b) `ten` c)
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public export
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interface Bifunctor ten => Symmetric ten where
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swap : a `ten` b -> b `ten` a
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public export
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interface Associative ten => Tensor ten i | ten where
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unitl : Isomorphism (i `ten` a) a
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unitr : Isomorphism (a `ten` i) a
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export
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Associative Pair where
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assoc = MkIso (\(x,(y,z)) => ((x,y),z)) (\((x,y),z) => (x,(y,z)))
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export
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Symmetric Pair where
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swap = Builtin.swap
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export
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Tensor Pair () where
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unitl = MkIso snd ((),)
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unitr = MkIso fst (,())
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export
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Associative Either where
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assoc = MkIso f b
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where
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f : forall a,b,c. Either a (Either b c) -> Either (Either a b) c
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f (Left x) = Left (Left x)
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f (Right (Left x)) = Left (Right x)
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f (Right (Right x)) = Right x
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b : forall a,b,c. Either (Either a b) c -> Either a (Either b c)
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b (Left (Left x)) = Left x
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b (Left (Right x)) = Right (Left x)
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b (Right x) = Right (Right x)
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export
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Symmetric Either where
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swap = either Right Left
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export
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Tensor Either Void where
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unitl = MkIso (either absurd id) Right
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unitr = MkIso (either id absurd) Left
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