572751c56e
Before this commit, we were inferring whether an inductive/structure/class were meta or not. This was bad since the user had no clue whether the type was trusted (non meta) or not. Moreover, users could get confused by this behavior and assume the kernel was allowing trusted code to rely on untrusted one.
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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meta 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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meta def 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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meta def 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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meta def 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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