3f80e530d3
This PR modifies pretty printing of `fun` binders, suppressing the safe shadowing feature among the binders in the same `fun`. For example, rather than pretty printing as `fun x x => 0`, we now see `fun x x_1 => 0`. The calculation is done per `fun`, so for example `fun x => id fun x => 0` pretty prints as-is, taking advantage of safe shadowing. The motivation for this change is that many users have reported that safe shadowing within the same `fun` is confusing.
68 lines
1.6 KiB
Text
68 lines
1.6 KiB
Text
import Lean
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open Lean
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open Lean.Meta
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inductive Vec (α : Type) : Nat → Type
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| nil : Vec α 0
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| cons {n} : α → Vec α n → Vec α (n+1)
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set_option trace.Meta.debug true
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def nat := mkConst `Nat
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def succ := mkConst `Nat.succ
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def tst1 : MetaM Unit :=
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withLocalDeclD `n nat fun n => do
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let n1 := mkApp succ n
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let vecN1 := mkApp2 (mkConst `Vec) nat n1
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withLocalDeclD `xs vecN1 fun xs => do
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generalizeTelescope #[n1, xs] fun ys => do
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let t ← mkLambdaFVars ys ys.back!
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trace[Meta.debug] t
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pure ()
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/-- trace: [Meta.debug] fun x x_1 => x_1 -/
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#guard_msgs in
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#eval tst1
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set_option pp.all true
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def tst2 : MetaM Unit :=
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withLocalDeclD `n nat fun n => do
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let n1 := mkApp succ n
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let vecN1 := mkApp2 (mkConst `Vec) nat n1
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withLocalDeclD `xs vecN1 $ fun xs => do
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let e ← mkEqRefl xs
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generalizeTelescope #[n1, xs, e] fun ys => do
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let t ← mkLambdaFVars ys ys.back!
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trace[Meta.debug] t
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pure ()
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/--
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trace: [Meta.debug] fun (x : Nat) (x_1 : Vec Nat x) (x_2 : @Eq.{1} (Vec Nat x) x_1 x_1) => x_2
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-/
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#guard_msgs in
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#eval tst2
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def failIfSuccess (x : MetaM Unit) : MetaM Unit := do
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let worked ← try x; pure true catch _ => pure false
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if worked then
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throwError "unexpected success"
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def tst3 : MetaM Unit :=
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withLocalDeclD `n nat $ fun n => do
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let n1 := mkApp succ n
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let vecN1 := mkApp2 (mkConst `Vec) nat n1
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withLocalDeclD `xs vecN1 $ fun xs => do
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let e ← mkEqRefl xs
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failIfSuccess do
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generalizeTelescope #[n1, e] fun ys => do
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let t ← mkLambdaFVars ys ys.back!
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trace[Meta.debug] t
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pure ()
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trace[Meta.debug] "failed as expected"
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/-- trace: [Meta.debug] failed as expected -/
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#guard_msgs in
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#eval tst3
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