9e30ac3265
This PR adds the predicate `Expr.fvarsSet a b`, which returns `true` if and only if the free variables in `a` are a subset of the free variables in `b`.
37 lines
1.1 KiB
Text
37 lines
1.1 KiB
Text
/-
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Copyright (c) 2020 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.Expr
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namespace Lean
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namespace Expr
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@[extern "lean_find_expr"]
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opaque findImpl? (p : @& (Expr → Bool)) (e : @& Expr) : Option Expr
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@[inline] def find? (p : Expr → Bool) (e : Expr) : Option Expr := findImpl? p e
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/-- Returns true if `e` occurs in `t` -/
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def occurs (e : Expr) (t : Expr) : Bool :=
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(t.find? fun s => s == e).isSome
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/--
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Returns type for `findExt?` function argument.
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-/
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inductive FindStep where
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| /-- Found desired subterm -/ found
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| /-- Search subterms -/ visit
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| /-- Do not search subterms -/ done
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@[extern "lean_find_ext_expr"]
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opaque findExtImpl? (p : @& (Expr → FindStep)) (e : @& Expr) : Option Expr
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/--
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Similar to `find?`, but `p` can return `FindStep.done` to interrupt the search on subterms.
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Remark: Differently from `find?`, we do not invoke `p` for partial applications of an application. -/
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@[inline] def findExt? (p : Expr → FindStep) (e : Expr) : Option Expr := findExtImpl? p e
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end Lean.Expr
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