29 lines
1.1 KiB
Text
29 lines
1.1 KiB
Text
/-
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Copyright (c) 2022 Mac Malone. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Mac Malone
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-/
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namespace Lake
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/-- A monad equipped with a dependently typed key-value store for a particular key. -/
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class MonadStore1 {κ : Type u} (k : κ) (α : outParam $ Type v) (m : Type v → Type w) where
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fetch? : m (Option α)
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store : α → m PUnit
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export MonadStore1 (fetch? store)
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/-- A monad equipped with a dependently typed key-object store. -/
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class MonadDStore (κ : Type u) (β : outParam $ κ → Type v) (m : Type v → Type w) where
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fetch? : (key : κ) → m (Option (β key))
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store : (key : κ) → β key → m PUnit
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instance [MonadDStore κ β m] : MonadStore1 k (β k) m where
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fetch? := MonadDStore.fetch? k
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store o := MonadDStore.store k o
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/-- A monad equipped with a key-object store. -/
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abbrev MonadStore κ α m := MonadDStore κ (fun _ => α) m
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instance [MonadLift m n] [MonadDStore κ β m] : MonadDStore κ β n where
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fetch? k := liftM (m := m) <| fetch? k
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store k a := liftM (m := m) <| store k a
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