60 lines
1.4 KiB
Text
60 lines
1.4 KiB
Text
import Lean
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new_frontend
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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] `aux $ 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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#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] `aux $ 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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#eval tst2
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def failIfSuccess (x : MetaM Unit) : MetaM Unit :=
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whenM («catch» (x *> pure true) (fun _ => pure false)) $
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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] `aux $ 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 "failed as expected"
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#eval tst3
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