32 lines
1 KiB
Text
32 lines
1 KiB
Text
/-
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Copyright (c) Luke Nelson and Jared Roesch. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Leonardo de Moura, Luke Nelson, Jared Roesch, Sebastian Ullrich
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-/
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prelude
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import init.control.applicative
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universes u v
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open function
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class has_bind (m : Type u → Type v) :=
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(bind : Π {α β : Type u}, m α → (α → m β) → m β)
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export has_bind (bind)
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@[inline] def has_bind.and_then {α β : Type u} {m : Type u → Type v} [has_bind m] (x : m α) (y : m β) : m β :=
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do x, y
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infixl ` >>= `:55 := bind
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infixl ` >> `:55 := has_bind.and_then
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class monad (m : Type u → Type v) extends applicative m, has_bind m : Type (max (u+1) v) :=
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(map := λ α β f x, x >>= pure ∘ f)
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(seq := λ α β f x, f >>= (<$> x))
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@[reducible, inline] def return {m : Type u → Type v} [monad m] {α : Type u} : α → m α :=
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pure
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/- Identical to has_bind.and_then, but it is not inlined. -/
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def has_bind.seq {α β : Type u} {m : Type u → Type v} [has_bind m] (x : m α) (y : m β) : m β :=
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do x, y
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