diff --git a/DocGen4/Load.lean b/DocGen4/Load.lean
index 1dd0717..5f23a57 100644
--- a/DocGen4/Load.lean
+++ b/DocGen4/Load.lean
@@ -46,7 +46,6 @@ def load (imports : List Name) : IO AnalyzerResult := do
   let env ← importModules (List.map (Import.mk · false) imports) Options.empty
   -- TODO parameterize maxHeartbeats
   IO.println "Processing modules"
-  let res ← Prod.fst <$> (Meta.MetaM.toIO process { maxHeartbeats := 100000000} { env := env} {} {})
-  return res
+  Prod.fst <$> (Meta.MetaM.toIO process { maxHeartbeats := 100000000, options := ⟨[(`pp.tagAppFns, true)]⟩ } { env := env} {} {})
 
 end DocGen4
diff --git a/DocGen4/Output/Module.lean b/DocGen4/Output/Module.lean
index 8bca416..460439e 100644
--- a/DocGen4/Output/Module.lean
+++ b/DocGen4/Output/Module.lean
@@ -5,6 +5,7 @@ Authors: Henrik Böving
 -/
 import Lean
 import Lean.PrettyPrinter
+import Lean.Widget.TaggedText
 
 import DocGen4.ToHtmlFormat
 import DocGen4.Output.Template
@@ -13,13 +14,41 @@ namespace DocGen4
 namespace Output
 
 open scoped DocGen4.Jsx
-open Lean PrettyPrinter
+open Lean PrettyPrinter Widget Elab
 
 def declNameToLink (name : Name) : HtmlM String := do
   let res ← getResult
   let module := res.moduleNames[res.name2ModIdx.find! name]
   (←moduleNameToLink module) ++ "#" ++ name.toString
 
+def splitWhitespaces (s : String) : (String × String × String) := Id.run do
+  let front := "".pushn ' ' (s.find (!Char.isWhitespace ·))
+  let mut s := s.trimLeft
+  let back := "".pushn ' ' (s.length - s.offsetOfPos (s.find Char.isWhitespace))
+  s:= s.trimRight
+  (front, s, back)
+
+partial def infoFormatToHtml (i : CodeWithInfos) : HtmlM (Array Html) := do
+  match i with
+  | TaggedText.text t => return #[t]
+  | TaggedText.append tt => tt.foldlM (λ acc t => do acc ++ (←infoFormatToHtml t)) #[]
+  | TaggedText.tag a t =>
+    match a.info.val.info with
+    | Info.ofTermInfo i =>
+      match i.expr.consumeMData with
+      | Expr.const name _ _ =>
+         match t with
+         | TaggedText.text t =>
+           let (front, t, back) := splitWhitespaces t
+           let elem := Html.element "a" true #[("href", ←declNameToLink name)] #[t]
+           #[Html.text front, elem, Html.text back]
+         | _ =>
+           -- TODO: Is this ever reachable?
+           #[Html.element "a" true #[("href", ←declNameToLink name)] (←infoFormatToHtml t)]
+      | _ =>
+         #[Html.element "span" true #[("class", "fn")] (←infoFormatToHtml t)]
+    | _ => #[Html.element "span" true #[("class", "fn")] (←infoFormatToHtml t)]
+
 def docInfoHeader (doc : DocInfo) : HtmlM Html := do
   let mut nodes := #[]
   -- TODO: noncomputable, partial
@@ -34,7 +63,7 @@ def docInfoHeader (doc : DocInfo) : HtmlM Html := do
     </span>
   -- TODO: Figure out how we can get explicit, implicit and TC args and put them here
   nodes := nodes.push <span «class»="decl_args">:</span>
-  nodes := nodes.push <div «class»="decl_type"><span «class»="fn">Type!!!</span></div>
+  nodes := nodes.push $ Html.element "div" true #[("class", "decl_type")] (←infoFormatToHtml doc.getType)
   -- TODO: The final type of the declaration
   return <div «class»="decl_header"> [nodes] </div>
 
@@ -57,7 +86,7 @@ def moduleToHtml (module : Module) : HtmlM Html := withReader (setCurrentName mo
   let docInfos ← module.members.mapM docInfoToHtml
   -- TODO: This is missing imports, imported by, source link, list of decls
   templateExtends (baseHtml module.name.toString) $
-    Html.element "main" #[] docInfos
+    Html.element "main" false #[] docInfos
 
 end Output
 end DocGen4
diff --git a/DocGen4/Process.lean b/DocGen4/Process.lean
index 486d77b..91d6693 100644
--- a/DocGen4/Process.lean
+++ b/DocGen4/Process.lean
@@ -13,34 +13,35 @@ import DocGen4.Hierarchy
 
 namespace DocGen4
 
-open Lean Meta PrettyPrinter Std
-
-abbrev InfoFormat := (Format × RBMap Delaborator.Pos Elab.Info compare)
+open Lean Meta PrettyPrinter Std Widget
 
 structure NameInfo where
   name  : Name
-  type : InfoFormat
-
-def NameInfo.prettyPrint (i : NameInfo) : String :=
-  s!"{i.name} : {i.type.fst}"
+  type : CodeWithInfos
+  deriving Inhabited
 
 structure Info extends NameInfo where
   doc : Option String
   declarationRange : DeclarationRange
+  deriving Inhabited
 
 structure AxiomInfo extends Info where
   isUnsafe : Bool
+  deriving Inhabited
 
 structure TheoremInfo extends Info
+  deriving Inhabited
 
 structure OpaqueInfo extends Info where
-  value : InfoFormat
+  value : CodeWithInfos
   isUnsafe : Bool
+  deriving Inhabited
 
 structure DefinitionInfo extends Info where
-  --value : InfoFormat
+  --value : CodeWithInfos
   unsafeInformation : DefinitionSafety
   hints : ReducibilityHints
+  deriving Inhabited
 
 abbrev InstanceInfo := DefinitionInfo
 
@@ -53,19 +54,23 @@ structure InductiveInfo extends Info where
   isUnsafe : Bool
   isReflexive : Bool
   isNested : Bool
+  deriving Inhabited
 
 structure FieldInfo extends NameInfo where
   projFn : Name
   subobject? : Option Name
+  deriving Inhabited
 
 structure StructureInfo extends Info where
   fieldInfo : Array FieldInfo
   parents : Array Name
   ctor : NameInfo
+  deriving Inhabited
 
 structure ClassInfo extends StructureInfo where
   hasOutParam : Bool
-  instances : Array InfoFormat
+  instances : Array CodeWithInfos
+  deriving Inhabited
 
 inductive DocInfo where
 | axiomInfo (info : AxiomInfo) : DocInfo
@@ -76,6 +81,7 @@ inductive DocInfo where
 | inductiveInfo (info : InductiveInfo) : DocInfo
 | structureInfo (info : StructureInfo) : DocInfo
 | classInfo (info : ClassInfo) : DocInfo
+  deriving Inhabited
 
 structure Module where
   name : Name
@@ -83,13 +89,18 @@ structure Module where
   members : Array DocInfo
   deriving Inhabited
 
-def prettyPrintTerm (expr : Expr) : MetaM InfoFormat := do
-  let ((expr, _), _) ← Elab.Term.TermElabM.run $ Elab.Term.levelMVarToParam (←instantiateMVars expr)
-  let (stx, info) ← delabCore Name.anonymous [] expr
-  let stx := sanitizeSyntax stx |>.run' { options := ←getOptions }
-  let stx ← parenthesizeTerm stx
-  let fmt ← PrettyPrinter.formatTerm stx
-  (fmt, info)
+def prettyPrintTerm (expr : Expr) : MetaM CodeWithInfos := do
+  let (fmt, infos) ← formatInfos expr
+  let tt := TaggedText.prettyTagged fmt
+  let ctx := {
+    env := ← getEnv
+    mctx := ← getMCtx
+    options := ← getOptions
+    currNamespace := ← getCurrNamespace
+    openDecls := ← getOpenDecls
+    fileMap := arbitrary
+  }
+  tagExprInfos ctx infos tt
 
 def Info.ofConstantVal (v : ConstantVal) : MetaM Info := do
   let env ← getEnv
@@ -122,7 +133,7 @@ def DefinitionInfo.ofDefinitionVal (v : DefinitionVal) : MetaM DefinitionInfo :=
   --let value ← prettyPrintTerm v.value
   return DefinitionInfo.mk info v.safety v.hints
 
-def getConstructorType (ctor : Name) : MetaM InfoFormat := do
+def getConstructorType (ctor : Name) : MetaM CodeWithInfos := do
   let env ← getEnv
   match env.find? ctor with
   | some (ConstantInfo.ctorInfo i) => ←prettyPrintTerm i.type
@@ -233,25 +244,6 @@ def ofConstant : (Name × ConstantInfo) → MetaM (Option DocInfo) := λ (name,
   | ConstantInfo.recInfo i => none
   | ConstantInfo.quotInfo i => none
 
-def prettyPrint (i : DocInfo) : CoreM String := do
-  match i with
-  | axiomInfo i => s!"axiom {i.toNameInfo.prettyPrint}, doc string: {i.doc}"
-  | theoremInfo i => s!"theorem {i.toNameInfo.prettyPrint}, doc string: {i.doc}"
-  | opaqueInfo i => s!"constant {i.toNameInfo.prettyPrint}, doc string: {i.doc}"
-  | definitionInfo i => s!"def {i.toNameInfo.prettyPrint}, doc string: {i.doc}"
-  | instanceInfo i => s!"instance {i.toNameInfo.prettyPrint}, doc string: {i.doc}"
-  | inductiveInfo i =>
-    let ctorString := i.ctors.map NameInfo.prettyPrint
-    s!"inductive {←i.toNameInfo.prettyPrint}, ctors: {ctorString}, doc string: {i.doc}"
-  | structureInfo i =>
-    let ctorString := i.ctor.prettyPrint
-    let fieldString := i.fieldInfo.map (λ f => s!"{f.name} : {f.type.fst}")
-    s!"structure {i.toNameInfo.prettyPrint} extends {i.parents}, ctor: {ctorString}, fields : {fieldString}, doc string: {i.doc}"
-  | classInfo i =>
-    let instanceString := i.instances.map Prod.fst
-    let fieldString := i.fieldInfo.map (NameInfo.prettyPrint ∘ FieldInfo.toNameInfo)
-    s!"class {i.toNameInfo.prettyPrint} extends {i.parents}, fields: {fieldString}, instances : {instanceString}, doc string: {i.doc}"
-
 def getName : DocInfo → Name
 | axiomInfo i => i.name
 | theoremInfo i => i.name
@@ -272,7 +264,7 @@ def getKind : DocInfo → String
 | structureInfo _ => "structure"
 | classInfo _ => "class" -- TODO: This is handled as structure right now
 
-def getType : DocInfo → InfoFormat
+def getType : DocInfo → CodeWithInfos
 | axiomInfo i => i.type
 | theoremInfo i => i.type
 | opaqueInfo i => i.type
@@ -284,14 +276,6 @@ def getType : DocInfo → InfoFormat
 
 end DocInfo
 
-namespace Module
-
-def prettyPrint (m : Module) : CoreM String := do
-  let pretty := s!"Module {m.name}, doc string: {m.doc} with members:\n"
-  Array.foldlM (λ p mem => return p ++ "  " ++ (←mem.prettyPrint) ++ "\n") pretty m.members
-
-end Module
-
 structure AnalyzerResult where
   name2ModIdx : HashMap Name ModuleIdx
   moduleNames : Array Name
diff --git a/lean-toolchain b/lean-toolchain
index 8b6c918..dcca6df 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:nightly-2021-12-12
+lean4