79 lines
3.5 KiB
Text
79 lines
3.5 KiB
Text
/-
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Copyright (c) 2016 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 init.meta.expr init.meta.name
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/-
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Reducibility hints are used in the convertibility checker.
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When trying to solve a constraint such a
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(f ...) =?= (g ...)
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where f and g are definitions, the checker has to decide which one will be unfolded.
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If f (g) is opaque, then g (f) is unfolded if it is also not marked as opaque,
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Else if f (g) is abbrev, then f (g) is unfolded if g (f) is also not marked as abbrev,
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Else if f and g are regular, then we unfold the one with the biggest definitional height.
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Otherwise both are unfolded.
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The arguments of the `regular` constructor are: the definitional height and the flag `self_opt`.
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The definitional height is by default computed by the kernel. It only takes into account
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other regular definitions used in a definition. When creating declarations using meta-programming,
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we can specify the definitional depth manually.
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For definitions marked as regular, we also have a hint for constraints such as
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(f a) =?= (f b)
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if self_opt == true, then checker will first try to solve (a =?= b), only if it fails,
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it unfolds f.
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Remark: the hint only affects performance. None of the hints prevent the kernel from unfolding a
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declaration during type checking.
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Remark: the reducibility_hints are not related to the attributes: reducible/irrelevance/semireducible.
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These attributes are used by the elaborator. The reducibility_hints are used by the kernel (and elaborator).
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Moreover, the reducibility_hints cannot be changed after a declaration is added to the kernel.
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-/
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inductive reducibility_hints
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| opaque : reducibility_hints
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| abbrev : reducibility_hints
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| regular : nat → bool → reducibility_hints
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/- Reflect a C++ declaration object. The VM replaces it with the C++ implementation. -/
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inductive declaration
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/- definition: name, list universe parameters, type, value, is_trusted -/
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| defn : name → list name → expr → expr → reducibility_hints → bool → declaration
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/- theorem: name, list universe parameters, type, value (remark: theorems are always trusted) -/
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| thm : name → list name → expr → expr → declaration
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/- constant assumption: name, list universe parameters, type, is_trusted -/
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| cnst : name → list name → expr → bool → declaration
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/- axiom : name → list universe parameters, type (remark: axioms are always trusted) -/
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| ax : name → list name → expr → declaration
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definition declaration.to_name : declaration → name
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| (declaration.defn n ls t v h tr) := n
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| (declaration.thm n ls t v) := n
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| (declaration.cnst n ls t tr) := n
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| (declaration.ax n ls t) := n
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definition declaration.univ_params : declaration → list name
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| (declaration.defn n ls t v h tr) := ls
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| (declaration.thm n ls t v) := ls
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| (declaration.cnst n ls t tr) := ls
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| (declaration.ax n ls t) := ls
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definition declaration.type : declaration → expr
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| (declaration.defn n ls t v h tr) := t
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| (declaration.thm n ls t v) := t
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| (declaration.cnst n ls t tr) := t
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| (declaration.ax n ls t) := t
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/- Instantiate a universe polymorphic declaration type with the given universes. -/
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meta_constant declaration.instantiate_type_univ_params : declaration → list level → option expr
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/- Instantiate a universe polymorphic declaration value with the given universes. -/
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meta_constant declaration.instantiate_value_univ_params : declaration → list level → option expr
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