feat: print nameless instances properly

DocGen4/Output/Module.lean

@@ -30,7 +30,10 @@ def argToHtml (arg : Arg) : HtmlM Html := do
   | BinderInfo.implicit => ("{", "}", true)
   | BinderInfo.strictImplicit => ("⦃", "⦄", true)
   | BinderInfo.instImplicit => ("[", "]", true)
-  let mut nodes := #[Html.text s!"{l}{arg.name.toString} : "]
+  let mut nodes :=
+    match arg.name with
+    | some name => #[Html.text s!"{l}{name.toString} : "]
+    | none => #[Html.text s!"{l}"]
   nodes := nodes.append (← infoFormatToHtml arg.type)
   nodes := nodes.push r
   let inner := <span class="fn">[nodes]</span>

DocGen4/Process/Base.lean

@@ -27,14 +27,16 @@ structure NameInfo where
   doc : Option String
   deriving Inhabited
 
+
 /--
 An argument to a declaration, e.g. the `(x : Nat)` in `def foo (x : Nat) := x`.
 -/
 structure Arg where
   /--
-  The name of the argument.
+  The name of the argument. For auto generated argument names like `[Monad α]`
+  this is none
   -/
-  name : Name
+  name : Option Name
   /--
   The pretty printed type of the argument.
   -/

DocGen4/Process/NameInfo.lean

@@ -15,17 +15,20 @@ def NameInfo.ofTypedName (n : Name) (t : Expr) : MetaM NameInfo := do
   let env ← getEnv
   return { name := n, type := ← prettyPrintTerm t, doc := ← findDocString? env n}
 
-partial def typeToArgsType (e : Expr) : (Array (Name × Expr × BinderInfo) × Expr) :=
+partial def typeToArgsType (e : Expr) : (Array ((Option Name) × Expr × BinderInfo) × Expr) :=
   let helper := fun name type body data =>
     -- Once we hit a name with a macro scope we stop traversing the expression
     -- and print what is left after the : instead. The only exception
     -- to this is instances since these almost never have a name
     -- but should still be printed as arguments instead of after the :.
-    if name.hasMacroScopes && !data.isInstImplicit then
+    if data.isInstImplicit then
+      let arg := (none, type, data)
+      let (args, final) := typeToArgsType (Expr.instantiate1 body (mkFVar ⟨name⟩))
+      (#[arg] ++ args, final)
+    else if name.hasMacroScopes then
       (#[], e)
     else
-      let name := name.eraseMacroScopes
-      let arg := (name, type, data)
+      let arg := (some name, type, data)
       let (args, final) := typeToArgsType (Expr.instantiate1 body (mkFVar ⟨name⟩))
       (#[arg] ++ args, final)
   match e.consumeMData with