e9d85f49e6
Based on the discussion at https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/for.2C.20unexpected.20need.20for.20type.20ascription/near/269083574 The consensus seemed to be that "auto pure" is more confusing than its worth.
36 lines
1.7 KiB
Text
36 lines
1.7 KiB
Text
import Lean
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open Lean Meta
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#eval show MetaM Unit from do
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let e ← withLetDecl `y (mkConst ``Nat) (mkConst ``Nat.zero) fun y => do
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let m ← mkFreshExprMVar (mkConst ``Nat)
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assignExprMVar m.mvarId! y
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let e := mkApp2 (mkConst ``Nat.add) m y
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-- goal: construct λ y, e
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dbg_trace (← ppExpr (← mkLambdaFVars #[y] e)) -- doesn't work: creates let
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dbg_trace (← ppExpr (← instantiateMVars <| -- doesn't work: contains free variable
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mkLambda `y BinderInfo.default (mkConst ``Nat) (e.abstract #[y])))
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instantiateMVars <| -- doesn't work: contains free variable
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mkLambda `y BinderInfo.default (mkConst ``Nat) (e.abstract #[y])
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dbg_trace (← ppExpr e)
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#eval show MetaM Unit from
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withLetDecl `y (mkConst ``Nat) (mkConst ``Nat.zero) fun y => do
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let m ← mkFreshExprMVar (mkConst ``Nat)
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assignExprMVar m.mvarId! y
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let e := mkApp2 (mkConst ``Nat.add) m y
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-- goal: construct λ y, e
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dbg_trace (← instantiateMVars <| -- doesn't work: contains free variable
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mkLambda `y BinderInfo.default (mkConst ``Nat) (← abstract e #[y]))
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#eval show MetaM Unit from do
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let (e, m) ← withLetDecl `y (mkConst ``Nat) (mkConst ``Nat.zero) fun y => do
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let m ← mkFreshExprMVar (mkConst ``Nat) (kind := MetavarKind.syntheticOpaque)
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let e := mkApp2 (mkConst ``Nat.add) m y
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dbg_trace (← ppExpr e)
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dbg_trace (← ppExpr (← abstract e #[y]))
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let e ← instantiateMVars <| -- doesn't work: contains free variable
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mkLambda `y BinderInfo.default (mkConst ``Nat) (← abstract e #[y])
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assignExprMVar m.mvarId! (mkApp2 (mkConst ``Nat.add) y y)
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return (e, m)
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dbg_trace (← ppExpr (← instantiateMVars e))
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