lean4-htt/library/init/lean/compiler/util.lean
Leonardo de Moura 681f3ec81b fix(library/compiler/llnf): constructor reuse
We were not reusing constructor values for constructors that contained only
scalar values.
2019-03-26 11:10:51 -07:00

58 lines
1.7 KiB
Text

/-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
prelude
import init.lean.expr
namespace Lean
namespace Compiler
def neutralExpr : Expr := Expr.const `_neutral []
def unreachableExpr : Expr := Expr.const `_unreachable []
def objectType : Expr := Expr.const `_obj []
def voidType : Expr := Expr.const `_void []
def mkLcProof (pred : Expr) := Expr.app (Expr.const `lcProof []) pred
namespace atMostOnce
structure AtMostOnceData :=
(found result : Bool)
def Visitor := AtMostOnceData → AtMostOnceData
@[inline] def seq (f g : Visitor) : Visitor :=
λ d, match f d with
| ⟨found, false⟩ := ⟨found, false⟩
| other := g other
@[inline] def skip : Visitor := id
@[inline] def visitFVar (x y : Name) : Visitor
| d@{result := false, ..} := d
| {found := false, result := true} := {found := x == y, result := true}
| {found := true, result := true} := {found := true, result := x != y}
local infix *> := seq
def visit (x : Name) : Expr → Visitor
| (Expr.fvar y) := visitFVar y x
| (Expr.app f a) := visit a *> visit f
| (Expr.lam _ _ d b) := visit d *> visit b
| (Expr.pi _ _ d b) := visit d *> visit b
| (Expr.elet _ t v b) := visit t *> visit v *> visit b
| (Expr.mdata _ e) := visit e
| (Expr.proj _ _ e) := visit e
| _ := skip
end atMostOnce
/-- Return true iff the free variable with id `x` occurs at most once in `e` -/
@[export lean.at_most_once_core]
def atMostOnce (e : Expr) (x : Name) : Bool :=
let {result := result, ..} := atMostOnce.visit x e {found := false, result := true} in
result
end Compiler
end Lean