feat: import private

src/Lean/Elab/Import.lean

@@ -11,9 +11,12 @@ import Lean.CoreM
 namespace Lean.Elab
 
 def headerToImports : TSyntax ``Parser.Module.header → Array Import
-  | `(Parser.Module.header| $[module%$moduleTk]? $[prelude%$preludeTk]? $[import $ns]*) =>
+  | `(Parser.Module.header| $[module%$moduleTk]? $[prelude%$preludeTk]? $importsStx*) =>
     let imports := if preludeTk.isNone then #[{ module := `Init : Import }] else #[]
-    imports ++ ns.map ({ module := ·.getId })
+    imports ++ importsStx.map fun
+      | `(Parser.Module.import| import $[private%$privateTk]? $n) =>
+        { module := n.getId, importPrivate := privateTk.isSome }
+      | _ => unreachable!
   | _ => unreachable!
 
 def processHeader (header : TSyntax ``Parser.Module.header) (opts : Options) (messages : MessageLog)

src/Lean/Elab/ParseImportsFast.lean

@@ -133,8 +133,8 @@ partial def whitespace : Parser := fun input s =>
   else
     false
 
-def State.pushModule (module : Name) (s : State) : State :=
-  { s with imports := s.imports.push { module } }
+def State.pushImport (i : Import) (s : State) : State :=
+  { s with imports := s.imports.push i }
 
 @[inline] def isIdRestCold (c : Char) : Bool :=
   c = '_' || c = '\'' || c == '!' || c == '?' || isLetterLike c || isSubScriptAlnum c
@@ -142,7 +142,7 @@ def State.pushModule (module : Name) (s : State) : State :=
 @[inline] def isIdRestFast (c : Char) : Bool :=
   c.isAlphanum || (c != '.' && c != '\n' && c != ' ' && isIdRestCold c)
 
-partial def moduleIdent : Parser := fun input s =>
+partial def moduleIdent (importPrivate : Bool) : Parser := fun input s =>
   let rec parse (module : Name) (s : State) :=
     let i := s.pos
     if h : input.atEnd i then
@@ -162,7 +162,7 @@ partial def moduleIdent : Parser := fun input s =>
             let s := s.next input s.pos
             parse module s
           else
-            whitespace input (s.pushModule module)
+            whitespace input (s.pushImport { module, importPrivate })
       else if isIdFirst curr then
         let startPart := i
         let s         := takeWhile isIdRestFast input (s.next' input i h)
@@ -172,7 +172,7 @@ partial def moduleIdent : Parser := fun input s =>
           let s := s.next input s.pos
           parse module s
         else
-          whitespace input (s.pushModule module)
+          whitespace input (s.pushImport { module, importPrivate })
       else
         s.mkError "expected identifier"
   parse .anonymous s
@@ -187,8 +187,8 @@ partial def moduleIdent : Parser := fun input s =>
 
 def main : Parser :=
   keywordCore "module" (fun _ s => { s with isModule := true }) (fun _ s => s) >>
-  keywordCore "prelude" (fun _ s => s.pushModule `Init) (fun _ s => s) >>
-  many (keyword "import" >> moduleIdent)
+  keywordCore "prelude" (fun _ s => s.pushImport `Init) (fun _ s => s) >>
+  many (keyword "import" >> keywordCore "private" (moduleIdent true) (moduleIdent false))
 
 end ParseImports
 

src/Lean/Environment.lean

@@ -94,7 +94,11 @@ instance : GetElem? (Array α) ModuleIdx α (fun a i => i.toNat < a.size) where
 abbrev ConstMap := SMap Name ConstantInfo
 
 structure Import where
-  module      : Name
+  module        : Name
+  /-- `import private`; whether to import and expose all data saved by the module. -/
+  importPrivate : Bool := false
+  /-- Whether to activate this import when the current module itself is imported. -/
+  isExported    : Bool := false
   deriving Repr, Inhabited
 
 instance : Coe Name Import := ⟨({module := ·})⟩

src/Lean/Parser/Module.lean

@@ -13,7 +13,8 @@ namespace Parser
 namespace Module
 def moduleTk   := leading_parser "module"
 def «prelude»  := leading_parser "prelude"
-def «import»   := leading_parser "import " >> identWithPartialTrailingDot
+def «private»  := leading_parser (withAnonymousAntiquot := false) "private"
+def «import»   := leading_parser "import " >> optional «private» >> identWithPartialTrailingDot
 def header     := leading_parser optional (moduleTk >> ppLine >> ppLine) >>
   optional («prelude» >> ppLine) >>
   many («import» >> ppLine) >>