ee5b652136
This PR adds documentation to builtin attributes like `@[refl]` or `@[implemented_by]`. Closes #8432 --------- Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk> Co-authored-by: David Thrane Christiansen <david@lean-fro.org>
32 lines
1.3 KiB
Text
32 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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Authors: Leonardo de Moura
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-/
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prelude
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import Lean.Environment
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import Lean.Attributes
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namespace Lean
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/--
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Instructs the compiler that function applications using the tagged declaration should not be
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extracted when they are closed terms, and that common subexpression elimination should not be
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performed.
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Ordinarily, the Lean compiler identifies closed terms (without free variables) and extracts them
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to top-level definitions. This optimization can prevent unnecessary recomputation of values.
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Preventing the extraction of closed terms is useful for declarations that have implicit effects
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that should be repeated.
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-/
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@[builtin_doc]
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builtin_initialize neverExtractAttr : TagAttribute ←
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registerTagAttribute `never_extract "instruct the compiler that function applications using the tagged declaration should not be extracted when they are closed terms, nor common subexpression should be performed. This is useful for declarations that have implicit effects."
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@[export lean_has_never_extract_attribute]
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partial def hasNeverExtractAttribute (env : Environment) (n : Name) : Bool :=
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let rec visit (n : Name) : Bool := neverExtractAttr.hasTag env n || (n.isInternal && visit n.getPrefix)
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visit n
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end Lean
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