44 lines
1.3 KiB
Text
44 lines
1.3 KiB
Text
/-
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Copyright (c) 2019 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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-/
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prelude
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import init.core
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universes u v w
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/- List-like type to avoid extra level of indirection -/
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inductive AssocList (α : Type u) (β : Type v)
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| nil {} : AssocList
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| cons (key : α) (value : β) (tail : AssocList) : AssocList
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namespace AssocList
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variables {α : Type u} {β : Type v} {δ : Type w}
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@[specialize] def foldl (f : δ → α → β → δ) : δ → AssocList α β → δ
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| d nil := d
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| d (cons a b es) := foldl (f d a b) es
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def find [HasBeq α] (a : α) : AssocList α β → Option β
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| nil := none
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| (cons k v es) := match k == a with
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| true := some v
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| false := find es
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def contains [HasBeq α] (a : α) : AssocList α β → Bool
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| nil := false
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| (cons k v es) := k == a || contains es
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def replace [HasBeq α] (a : α) (b : β) : AssocList α β → AssocList α β
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| nil := nil
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| (cons k v es) := match k == a with
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| true := cons a b es
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| false := cons k v (replace es)
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def erase [HasBeq α] (a : α) : AssocList α β → AssocList α β
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| nil := nil
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| (cons k v es) := match k == a with
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| true := es
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| false := cons k v (erase es)
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end AssocList
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