The delaborator is the first stage of the pretty printer, and the inverse of the elaborator: it turns fully elaborated Expr core terms back into surface-level Syntax, omitting some implicit information again and using higher-level syntax abstractions like notations where possible. The exact behavior can be customized using pretty printer options; activating pp.all should guarantee that the delaborator is injective and that re-elaborating the resulting Syntax round-trips.

Pretty printer options can be given not only for the whole term, but also specific subterms. This is used both when automatically refining pp options until round-trip and when interactively selecting pp options for a subterm (both TBD). The association of options to subterms is done by assigning a unique, synthetic Nat position to each subterm derived from its position in the full term. This position is added to the corresponding Syntax object so that elaboration errors and interactions with the pretty printer output can be traced back to the subterm.

The delaborator is extensible via the [delab] attribute.

structure Lean.PrettyPrinter.Delaborator.Context : Type

• optionsPerPos : Lean.PrettyPrinter.Delaborator.OptionsPerPos
• currNamespace : Lean.Name
• openDecls : List Lean.OpenDecl
• inPattern : Bool
• subExpr : Lean.SubExpr

structure Lean.PrettyPrinter.Delaborator.State : Type

• We attach Elab.Info at various locations in the Syntax output in order to convey its semantics. While the elaborator emits InfoTrees, here we have no real text location tree to traverse, so we use a flattened map.

  infos : Lean.SubExpr.PosMap Lean.Elab.Info

• See SubExpr.nextExtraPos.

  holeIter : Lean.PrettyPrinter.Delaborator.SubExpr.HoleIterator

opaque Lean.PrettyPrinter.Delaborator.delabFailureId : Lean.InternalExceptionId

@[inline]

abbrev Lean.PrettyPrinter.Delaborator.DelabM (α : Type) : Type

Equations

• Lean.PrettyPrinter.Delaborator.DelabM = ReaderT Lean.PrettyPrinter.Delaborator.Context (StateRefT' IO.RealWorld Lean.PrettyPrinter.Delaborator.State Lean.MetaM)

@[inline]

abbrev Lean.PrettyPrinter.Delaborator.Delab : Type

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• Lean.PrettyPrinter.Delaborator.Delab = Lean.PrettyPrinter.Delaborator.DelabM Lean.Term

instance Lean.PrettyPrinter.Delaborator.instInhabitedDelabM {α : Type} : Inhabited (Lean.PrettyPrinter.Delaborator.DelabM α)

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• Lean.PrettyPrinter.Delaborator.instInhabitedDelabM = { default := throw default }

@[inline]

def Lean.PrettyPrinter.Delaborator.orElse {α : Type} (d₁ : Lean.PrettyPrinter.Delaborator.DelabM α) (d₂ : Unit → Lean.PrettyPrinter.Delaborator.DelabM α) : Lean.PrettyPrinter.Delaborator.DelabM α

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• Lean.PrettyPrinter.Delaborator.orElse d₁ d₂ = Lean.catchInternalId Lean.PrettyPrinter.Delaborator.delabFailureId d₁ fun x => d₂ ()

def Lean.PrettyPrinter.Delaborator.failure {α : Type} : Lean.PrettyPrinter.Delaborator.DelabM α

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• Lean.PrettyPrinter.Delaborator.failure = throw (Lean.Exception.internal Lean.PrettyPrinter.Delaborator.delabFailureId)

instance Lean.PrettyPrinter.Delaborator.instAlternativeDelabM : Alternative Lean.PrettyPrinter.Delaborator.DelabM

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• Lean.PrettyPrinter.Delaborator.instAlternativeDelabM = Alternative.mk (fun {α} => Lean.PrettyPrinter.Delaborator.failure) fun {α} => Lean.PrettyPrinter.Delaborator.orElse

instance Lean.PrettyPrinter.Delaborator.instOrElseDelabM {α : Type} : OrElse (Lean.PrettyPrinter.Delaborator.DelabM α)

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• Lean.PrettyPrinter.Delaborator.instOrElseDelabM = { orElse := Lean.PrettyPrinter.Delaborator.orElse }

instance Lean.PrettyPrinter.Delaborator.instMonadReaderOfSubExprDelabM : MonadReaderOf Lean.SubExpr Lean.PrettyPrinter.Delaborator.DelabM

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• Lean.PrettyPrinter.Delaborator.instMonadReaderOfSubExprDelabM = { read := Lean.PrettyPrinter.Delaborator.Context.subExpr <$> read }

instance Lean.PrettyPrinter.Delaborator.instMonadWithReaderOfSubExprDelabM : MonadWithReaderOf Lean.SubExpr Lean.PrettyPrinter.Delaborator.DelabM

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instance Lean.PrettyPrinter.Delaborator.instMonadStateOfHoleIteratorDelabM : MonadStateOf Lean.PrettyPrinter.Delaborator.SubExpr.HoleIterator Lean.PrettyPrinter.Delaborator.DelabM

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instance Lean.PrettyPrinter.Delaborator.instMonadQuotationDelabM : Lean.MonadQuotation Lean.PrettyPrinter.Delaborator.DelabM

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• Lean.PrettyPrinter.Delaborator.instMonadQuotationDelabM = Lean.MonadQuotation.mk (pure default) (pure default) fun {α} x => x

unsafe def Lean.PrettyPrinter.Delaborator.mkDelabAttribute : IO (Lean.KeyedDeclsAttribute Lean.PrettyPrinter.Delaborator.Delab)

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opaque Lean.PrettyPrinter.Delaborator.delabAttribute : Lean.KeyedDeclsAttribute Lean.PrettyPrinter.Delaborator.Delab

def Lean.PrettyPrinter.Delaborator.getExprKind : Lean.PrettyPrinter.Delaborator.DelabM Lean.Name

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def Lean.PrettyPrinter.Delaborator.getOptionsAtCurrPos : Lean.PrettyPrinter.Delaborator.DelabM Lean.Options

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def Lean.PrettyPrinter.Delaborator.getPPOption (opt : Lean.Options → Bool) : Lean.PrettyPrinter.Delaborator.DelabM Bool

Evaluate option accessor, using subterm-specific options if set.

Equations

• Lean.PrettyPrinter.Delaborator.getPPOption opt = do let __do_lift ← Lean.PrettyPrinter.Delaborator.getOptionsAtCurrPos pure (opt __do_lift)

def Lean.PrettyPrinter.Delaborator.whenPPOption (opt : Lean.Options → Bool) (d : Lean.PrettyPrinter.Delaborator.Delab) : Lean.PrettyPrinter.Delaborator.Delab

Equations

• Lean.PrettyPrinter.Delaborator.whenPPOption opt d = do let b ← Lean.PrettyPrinter.Delaborator.getPPOption opt if b = true then d else failure

def Lean.PrettyPrinter.Delaborator.whenNotPPOption (opt : Lean.Options → Bool) (d : Lean.PrettyPrinter.Delaborator.Delab) : Lean.PrettyPrinter.Delaborator.Delab

Equations

• Lean.PrettyPrinter.Delaborator.whenNotPPOption opt d = do let b ← Lean.PrettyPrinter.Delaborator.getPPOption opt if b = true then failure else d

def Lean.PrettyPrinter.Delaborator.withOptionAtCurrPos {α : Type} (k : Lean.Name) (v : Lean.DataValue) (x : Lean.PrettyPrinter.Delaborator.DelabM α) : Lean.PrettyPrinter.Delaborator.DelabM α

Set the given option at the current position and execute x in this context.

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def Lean.PrettyPrinter.Delaborator.annotatePos (pos : Lean.SubExpr.Pos) (stx : Lean.Term) : Lean.Term

Equations

• Lean.PrettyPrinter.Delaborator.annotatePos pos stx = { raw := Lean.Syntax.setInfo (Lean.SourceInfo.synthetic { byteIdx := pos } { byteIdx := pos }) stx.raw }

def Lean.PrettyPrinter.Delaborator.annotateCurPos (stx : Lean.Term) : Lean.PrettyPrinter.Delaborator.Delab

Equations

• Lean.PrettyPrinter.Delaborator.annotateCurPos stx = do let __do_lift ← Lean.PrettyPrinter.Delaborator.SubExpr.getPos pure (Lean.PrettyPrinter.Delaborator.annotatePos __do_lift stx)

def Lean.PrettyPrinter.Delaborator.getUnusedName (suggestion : Lean.Name) (body : Lean.Expr) : Lean.PrettyPrinter.Delaborator.DelabM Lean.Name

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def Lean.PrettyPrinter.Delaborator.getUnusedName.bodyUsesSuggestion (body : Lean.Expr) (lctx : Lean.LocalContext) (suggestion' : Lean.Name) : Bool

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def Lean.PrettyPrinter.Delaborator.withBindingBodyUnusedName {α : Type} (d : Lean.Syntax → Lean.PrettyPrinter.Delaborator.DelabM α) : Lean.PrettyPrinter.Delaborator.DelabM α

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@[inline]

def Lean.PrettyPrinter.Delaborator.liftMetaM {α : Type} (x : Lean.MetaM α) : Lean.PrettyPrinter.Delaborator.DelabM α

Equations

• Lean.PrettyPrinter.Delaborator.liftMetaM x = liftM x

def Lean.PrettyPrinter.Delaborator.addTermInfo (pos : Lean.SubExpr.Pos) (stx : Lean.Syntax) (e : Lean.Expr) (isBinder : optParam Bool false) : Lean.PrettyPrinter.Delaborator.DelabM Unit

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def Lean.PrettyPrinter.Delaborator.addTermInfo.mkTermInfo (stx : Lean.Syntax) (e : Lean.Expr) (isBinder : optParam Bool false) : Lean.PrettyPrinter.Delaborator.DelabM Lean.Elab.Info

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def Lean.PrettyPrinter.Delaborator.addFieldInfo (pos : Lean.SubExpr.Pos) (projName : Lean.Name) (fieldName : Lean.Name) (stx : Lean.Syntax) (val : Lean.Expr) : Lean.PrettyPrinter.Delaborator.DelabM Unit

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def Lean.PrettyPrinter.Delaborator.addFieldInfo.mkFieldInfo (projName : Lean.Name) (fieldName : Lean.Name) (stx : Lean.Syntax) (val : Lean.Expr) : Lean.PrettyPrinter.Delaborator.DelabM Lean.Elab.Info

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def Lean.PrettyPrinter.Delaborator.annotateTermInfo (stx : Lean.Term) : Lean.PrettyPrinter.Delaborator.Delab

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partial def Lean.PrettyPrinter.Delaborator.delabFor : Lean.Name → Lean.PrettyPrinter.Delaborator.Delab

partial def Lean.PrettyPrinter.Delaborator.delab : Lean.PrettyPrinter.Delaborator.Delab

unsafe def Lean.PrettyPrinter.Delaborator.mkAppUnexpanderAttribute : IO (Lean.KeyedDeclsAttribute Lean.PrettyPrinter.Unexpander)

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opaque Lean.PrettyPrinter.Delaborator.appUnexpanderAttribute : Lean.KeyedDeclsAttribute Lean.PrettyPrinter.Unexpander

def Lean.PrettyPrinter.delabCore (e : Lean.Expr) (optionsPerPos : optParam Lean.PrettyPrinter.Delaborator.OptionsPerPos ∅) (delab : optParam Lean.PrettyPrinter.Delaborator.Delab Lean.PrettyPrinter.Delaborator.delab) : Lean.MetaM (Lean.Term × Lean.SubExpr.PosMap Lean.Elab.Info)

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def Lean.PrettyPrinter.delab (e : Lean.Expr) (optionsPerPos : optParam Lean.PrettyPrinter.Delaborator.OptionsPerPos ∅) : Lean.MetaM Lean.Term

"Delaborate" the given term into surface-level syntax using the default and given subterm-specific options.

Equations

• Lean.PrettyPrinter.delab e optionsPerPos = do let __discr ← Lean.PrettyPrinter.delabCore e optionsPerPos Lean.PrettyPrinter.Delaborator.delab match __discr with | (stx, snd) => pure stx